fix(ecstore): collapse ILM expiry worker env knobs to canonical name

2026-08-13 16:46:55 +00:00 · 2026-08-13 03:04:09 +08:00
176 changed files with 5526 additions and 19794 deletions
@@ -85,7 +85,7 @@ runs:
        repo-token: ${{ github.token }}

    - name: Install flatc
-      uses: Nugine/setup-flatc@698800de72a96bfb22cf60431dc21a2ff9a7e07b # v1
+      uses: Nugine/setup-flatc@e7855e994773ce90094a3f1626d4afc9080c23ae # v1
      with:
        version: "25.12.19"

@@ -131,9 +131,9 @@ module split is tracked under `docs/architecture/`.
     why it stays local).
   - ✅ RESOLVED: `BackpressureConfig` and `DataUsageInfo` each have exactly one
     definition (`crates/io-core/src/backpressure.rs`,
-     `crates/data-usage/src/data_usage.rs`). The zero-consumer
-     `BackpressureSettings` copy that lingered in io-metrics was removed
-     (rustfs/backlog#1833).
+     `crates/data-usage/src/data_usage.rs`). A zero-consumer
+     `BackpressureSettings` copy lingers in `crates/io-metrics/src/config.rs`;
+     its removal is tracked in rustfs/backlog#1833.

 4. **ecstore does not know about HTTP or S3 protocol details.** It operates on
   storage-level abstractions (objects, buckets, disks, pools).
@@ -1162,9 +1162,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-eventstream"
-version = "0.61.2"
+version = "0.61.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6de526c7b567420a31bc283657a7921b45c4cafe0827fdf2490713dcc770c28f"
+checksum = "5a9381123ab62d20c13082b151f30f962a3b112b727345394536dfa39a482944"
 dependencies = [
 "aws-smithy-types",
 "bytes",
@@ -1195,9 +1195,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-http-client"
-version = "1.3.0"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c1c8a04cb31ba74d0115af5a890bb8c0d48fba64b52812fa13929a6ef0cc83c"
+checksum = "635d23afda0a6ab48d666c4d447c4873e8d1e83518a2be2093122397e50b838e"
 dependencies = [
 "aws-smithy-async",
 "aws-smithy-protocol-test",
@@ -1277,9 +1277,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-runtime"
-version = "1.13.1"
+version = "1.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "483b858ff67522011c4786310c5cd8fd88d0be7ea3d5f1a48328446300c4269e"
+checksum = "07505b34e8f4b3591a4fa69e9792b52289b95488dbbc68c3c0075b7bedb245e1"
 dependencies = [
 "aws-smithy-async",
 "aws-smithy-http",
@@ -1343,9 +1343,9 @@ dependencies = [

 [[package]]
 name = "aws-smithy-types"
-version = "1.6.2"
+version = "1.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fce83ce9abbb198d25bc7131e468d0f9fe1257125e58c39f3f9fc9f5098c9647"
+checksum = "d6dc683efb34b9e755675b37fedbe0103141e5b6df7bdc9eb6967756a8c167d8"
 dependencies = [
 "base64-simd",
 "bytes",
@@ -5133,9 +5133,9 @@ dependencies = [

 [[package]]
 name = "http-body-util"
-version = "0.1.5"
+version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "23169fe34a5fbcdd3f3862e78fb9b6fccd5f02a6dc6f732547005d45631ce71c"
+checksum = "e9f41fd6a08e4d4ec69df65976da761afd5ad5e58a9d4acb46bd1c953a9e3ff2"
 dependencies = [
 "bytes",
 "futures-core",
@@ -5957,7 +5957,7 @@ checksum = "b6d2cec3eae94f9f509c767b45932f1ada8350c4bdb85af2fcab4a3c14807981"
 [[package]]
 name = "libmimalloc-sys"
 version = "0.1.49"
-source = "git+https://github.com/xonatius/mimalloc_rust.git?rev=6d4c41bb10c6d9da1d1b6f07b38c4cc051667f11#6d4c41bb10c6d9da1d1b6f07b38c4cc051667f11"
+source = "git+https://github.com/xonatius/mimalloc_rust.git?rev=ce6338661179c8be22e516b00af7483f151485a7#ce6338661179c8be22e516b00af7483f151485a7"
 dependencies = [
 "cc",
 "cty",
@@ -6259,9 +6259,9 @@ dependencies = [

 [[package]]
 name = "metrique"
-version = "0.1.30"
+version = "0.1.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dedbf06ffeef4c37990c73636fbd993aa34fb1948afd736e6114f239220993db"
+checksum = "d2e394c63e2d1a30aeb3b9392ecf3439d8475d2df810a8f4f6e66d6866754017"
 dependencies = [
 "itoa",
 "jiff",
@@ -6289,9 +6289,9 @@ dependencies = [

 [[package]]
 name = "metrique-macro"
-version = "0.1.21"
+version = "0.1.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f4fb1f30185f53f7f6e4c9e46745c1a1350af8e77fda5a88aded44b0637a82e0"
+checksum = "786df1fd0abebd0db685f7e9a353c78756d4b370fb98a52376c2015fa55f141f"
 dependencies = [
 "Inflector",
 "darling 0.23.0",
@@ -6318,9 +6318,9 @@ checksum = "2faca4e4480069ff02b1763b3b79f5cec7e8628e24d9dc5b6073f53d2577a4d9"

 [[package]]
 name = "metrique-writer"
-version = "0.1.26"
+version = "0.1.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "20bd17c1a3ca2719e31f19ce77a853948dc2102f35976b92276c42a64fdc5f3f"
+checksum = "82cdde44d241dab7fc8b7a32e0eb5dae6cd28f8de80b59f9a1e9f2f0b05e485e"
 dependencies = [
 "ahash",
 "crossbeam-queue",
@@ -6339,9 +6339,9 @@ dependencies = [

 [[package]]
 name = "metrique-writer-core"
-version = "0.1.20"
+version = "0.1.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f1a55b6aae1d85c557c729564c4e2b32a26dc65ba2d90d9647ca01f2bd4854c4"
+checksum = "e57379b7ee2272efaeaaa6de062503563e57333b24aadc7f2255b3d602899e8b"
 dependencies = [
 "derive-where",
 "itertools 0.14.0",
@@ -6366,7 +6366,7 @@ dependencies = [
 [[package]]
 name = "mimalloc"
 version = "0.1.52"
-source = "git+https://github.com/xonatius/mimalloc_rust.git?rev=6d4c41bb10c6d9da1d1b6f07b38c4cc051667f11#6d4c41bb10c6d9da1d1b6f07b38c4cc051667f11"
+source = "git+https://github.com/xonatius/mimalloc_rust.git?rev=ce6338661179c8be22e516b00af7483f151485a7#ce6338661179c8be22e516b00af7483f151485a7"
 dependencies = [
 "libmimalloc-sys",
 ]
@@ -6882,7 +6882,7 @@ version = "5.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "51e219e79014df21a225b1860a479e2dcd7cbd9130f4defd4bd0e191ea31d67d"
 dependencies = [
- "base64 0.21.7",
+ "base64 0.22.1",
 "chrono",
 "getrandom 0.2.17",
 "http 1.5.0",
@@ -8043,7 +8043,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "be769465445e8c1474e9c5dac2018218498557af32d9ed057325ec9a41ae81bf"
 dependencies = [
 "heck 0.5.0",
- "itertools 0.10.5",
+ "itertools 0.14.0",
 "log",
 "multimap",
 "once_cell",
@@ -8063,7 +8063,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "03da047801ff44bb6a4d407d4860c05fd70bb81714e6b2f3812603d5b145b042"
 dependencies = [
 "heck 0.5.0",
- "itertools 0.10.5",
+ "itertools 0.14.0",
 "log",
 "multimap",
 "petgraph 0.8.3",
@@ -8084,7 +8084,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a56d757972c98b346a9b766e3f02746cde6dd1cd1d1d563472929fdd74bec4d"
 dependencies = [
 "anyhow",
- "itertools 0.10.5",
+ "itertools 0.14.0",
 "proc-macro2",
 "quote",
 "syn 2.0.119",
@@ -8097,7 +8097,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b570b25f7617e43d59005d0990ccb79e950a423952cea19671b7a876da390adf"
 dependencies = [
 "anyhow",
- "itertools 0.10.5",
+ "itertools 0.14.0",
 "proc-macro2",
 "quote",
 "syn 2.0.119",
@@ -9201,6 +9201,7 @@ dependencies = [
 "sha2 0.11.0",
 "shadow-rs",
 "socket2",
+ "starshard",
 "subtle",
 "sysinfo",
 "temp-env",
@@ -9620,7 +9621,9 @@ dependencies = [
 "metrics",
 "metrics-util",
 "num_cpus",
+ "rustfs-common",
 "rustfs-s3-ops",
+ "rustfs-utils",
 "sysinfo",
 "thiserror 2.0.20",
 "tokio",
@@ -9734,7 +9737,6 @@ dependencies = [
 "rustfs-utils",
 "rustify",
 "serde",
- "serde_ignored",
 "serde_json",
 "sha2 0.11.0",
 "subtle",
@@ -10559,9 +10561,9 @@ dependencies = [

 [[package]]
 name = "rustls-connector"
-version = "0.23.8"
+version = "0.23.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1babecfcc65b139b812e74bcc7f9ec7b4e00db659fd42d99567b7e77f0c714c6"
+checksum = "09a5abe04eec18f8b9fbe87885bcaee6426de80bbc579958c0bc064b728ee617"
 dependencies = [
 "futures-io",
 "futures-rustls",
@@ -10937,16 +10939,6 @@ dependencies = [
 "syn 3.0.3",
 ]

-[[package]]
-name = "serde_ignored"
-version = "0.1.14"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "115dffd5f3853e06e746965a20dcbae6ee747ae30b543d91b0e089668bb07798"
-dependencies = [
- "serde",
- "serde_core",
-]
-
 [[package]]
 name = "serde_json"
 version = "1.0.151"
@@ -11800,7 +11792,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
 dependencies = [
 "fastrand",
- "getrandom 0.3.4",
+ "getrandom 0.4.3",
 "once_cell",
 "rustix",
 "windows-sys 0.61.2",
@@ -154,7 +154,7 @@ hyper-rustls = { default-features = false, version = "0.27.9" }
 hyper-util = { version = "0.1.20" }
 http = "1.5.0"
 http-body = "1.1.0"
-http-body-util = "0.1.5"
+http-body-util = "0.1.4"
 minlz = "1.2.3"
 reqwest = "0.13.4"
 rustfs-kafka-async = { version = "1.2.0" }
@@ -182,7 +182,6 @@ quick-xml = "0.41.0"
 rmp = { version = "0.8.15" }
 rmp-serde = { version = "1.3.1" }
 serde = { version = "1.0.229" }
-serde_ignored = { version = "0.1" }
 serde_json = { version = "1.0.151" }
 serde_urlencoded = "0.7.1"

@@ -231,9 +230,9 @@ aws-credential-types = { version = "1.3.0" }
 aws-sdk-kms = { default-features = false, version = "1.114.0" }
 aws-sdk-s3 = { default-features = false, version = "1.141.0" }
 aws-sdk-sts = { default-features = false, version = "1.110.0" }
-aws-smithy-http-client = { default-features = false, version = "1.3.0" }
+aws-smithy-http-client = { default-features = false, version = "1.2.0" }
 aws-smithy-runtime-api = { version = "1.14.0" }
-aws-smithy-types = { version = "1.6.2" }
+aws-smithy-types = { version = "1.6.1" }
 base64 = "0.23.1"
 base64-simd = "0.8.0"
 brotli = "8.0.4"
@@ -348,8 +347,8 @@ russh-sftp = "2.4.0"
 dav-server = "0.11.0"

 # Performance Analysis and Memory Profiling
-mimalloc = { version = "0.1.52", git = "https://github.com/xonatius/mimalloc_rust.git", rev = "6d4c41bb10c6d9da1d1b6f07b38c4cc051667f11" }
-libmimalloc-sys = { version = "0.1.49", git = "https://github.com/xonatius/mimalloc_rust.git", rev = "6d4c41bb10c6d9da1d1b6f07b38c4cc051667f11", features = ["extended"] }
+mimalloc = { version = "0.1.52", git = "https://github.com/xonatius/mimalloc_rust.git", rev = "ce6338661179c8be22e516b00af7483f151485a7" }
+libmimalloc-sys = { version = "0.1.49", git = "https://github.com/xonatius/mimalloc_rust.git", rev = "ce6338661179c8be22e516b00af7483f151485a7", features = ["extended"] }
 hotpath = { version = "0.23.2", default-features = false }
 # Snapshot testing for output format regression detection
 insta = { version = "1.48" }
@@ -21,13 +21,6 @@ use crate::{
    Xxhash3, Xxhash64, Xxhash128,
 };

-// DELIBERATE DUPLICATION of the x-amz-checksum-* names that also exist as
-// AMZ_CHECKSUM_* in rustfs-utils' headers module (crates/utils/src/http/
-// headers.rs): this crate is a zero-internal-dependency leaf, so it cannot
-// import them, and it additionally owns the RustFS extension names
-// (sha512/xxhash*) that utils does not carry. Values are pinned by the S3
-// wire protocol; do not merge without a maintainer decision on the leaf
-// boundary (backlog#1833).
 pub const CRC_32_HEADER_NAME: &str = "x-amz-checksum-crc32";
 pub const CRC_32_C_HEADER_NAME: &str = "x-amz-checksum-crc32c";
 pub const SHA_1_HEADER_NAME: &str = "x-amz-checksum-sha1";
@@ -41,14 +41,6 @@ pub const XXHASH_64_NAME: &str = "xxhash64";
 pub const XXHASH_128_NAME: &str = "xxhash128";
 pub const MD5_NAME: &str = "md5";

-/// One of three deliberately separate checksum registries (backlog#1833):
-/// this enum owns the **streaming-hash algorithm registry**, including the
-/// RustFS extensions (sha512, xxhash3/64/128). The on-disk xl.meta bitset
-/// lives in `rustfs_rio::ChecksumType` (crates/rio/src/checksum.rs, varint
-/// bits are append-only), and the MinIO-port client keeps its own
-/// `ChecksumMode` (crates/ecstore/src/client/checksum.rs). When adding an
-/// algorithm, extend all three (or record why not) — they do not derive from
-/// each other.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 #[non_exhaustive]
 pub enum ChecksumAlgorithm {
@@ -0,0 +1,87 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use crate::last_minute::{self};
+use std::collections::HashMap;
+
+pub struct ReplicationLatency {
+    // Delays for single and multipart PUT requests
+    upload_histogram: last_minute::LastMinuteHistogram,
+}
+
+impl ReplicationLatency {
+    // Merge two ReplicationLatency
+    pub fn merge(&mut self, other: &mut ReplicationLatency) -> &ReplicationLatency {
+        self.upload_histogram.merge(&other.upload_histogram);
+        self
+    }
+
+    // Get upload delay (categorized by object size interval)
+    pub fn get_upload_latency(&mut self) -> HashMap<String, u64> {
+        let mut ret = HashMap::new();
+        let avg = self.upload_histogram.get_avg_data();
+        for (i, v) in avg.iter().enumerate() {
+            let avg_duration = v.avg();
+            ret.insert(self.size_tag_to_string(i), avg_duration.as_millis() as u64);
+        }
+        ret
+    }
+    pub fn update(&mut self, size: i64, during: std::time::Duration) {
+        self.upload_histogram.add(size, during);
+    }
+
+    // Simulate the conversion from size tag to string
+    fn size_tag_to_string(&self, tag: usize) -> String {
+        match tag {
+            0 => String::from("Size < 1 KiB"),
+            1 => String::from("Size < 1 MiB"),
+            2 => String::from("Size < 10 MiB"),
+            3 => String::from("Size < 100 MiB"),
+            4 => String::from("Size < 1 GiB"),
+            _ => String::from("Size > 1 GiB"),
+        }
+    }
+}
+
+// #[derive(Debug, Clone, Default)]
+// pub struct ReplicationLastMinute {
+//     pub last_minute: LastMinuteLatency,
+// }
+
+// impl ReplicationLastMinute {
+//     pub fn merge(&mut self, other: ReplicationLastMinute) -> ReplicationLastMinute {
+//         let mut nl = ReplicationLastMinute::default();
+//         nl.last_minute = self.last_minute.merge(&mut other.last_minute);
+//         nl
+//     }
+
+//     pub fn add_size(&mut self, n: i64) {
+//         let t = SystemTime::now()
+//             .duration_since(UNIX_EPOCH)
+//             .expect("Time went backwards")
+//             .as_secs();
+//         self.last_minute.add_all(t - 1, &AccElem { total: t - 1, size: n as u64, n: 1 });
+//     }
+
+//     pub fn get_total(&self) -> AccElem {
+//         self.last_minute.get_total()
+//     }
+// }
+
+// impl fmt::Display for ReplicationLastMinute {
+//     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+//         let t = self.last_minute.get_total();
+//         write!(f, "ReplicationLastMinute sz= {}, n= {}, dur= {}", t.size, t.n, t.total)
+//     }
+// }
@@ -572,3 +572,44 @@ mod tests {
        assert_eq!(total.n, 6);
    }
 }
+
+const SIZE_LAST_ELEM_MARKER: usize = 10; // Assumed marker size is 10, modify according to actual situation
+
+#[allow(dead_code)]
+#[derive(Debug, Default)]
+pub struct LastMinuteHistogram {
+    histogram: Vec<LastMinuteLatency>,
+    size: u32,
+}
+
+impl LastMinuteHistogram {
+    pub fn merge(&mut self, other: &LastMinuteHistogram) {
+        for i in 0..self.histogram.len() {
+            self.histogram[i].merge(&other.histogram[i]);
+        }
+    }
+
+    pub fn add(&mut self, size: i64, t: Duration) {
+        let index = size_to_tag(size);
+        self.histogram[index].add(&t);
+    }
+
+    pub fn get_avg_data(&mut self) -> [AccElem; SIZE_LAST_ELEM_MARKER] {
+        let mut res = [AccElem::default(); SIZE_LAST_ELEM_MARKER];
+        for (i, elem) in self.histogram.iter_mut().enumerate() {
+            res[i] = elem.get_total();
+        }
+        res
+    }
+}
+
+fn size_to_tag(size: i64) -> usize {
+    match size {
+        _ if size < 1024 => 0,               // sizeLessThan1KiB
+        _ if size < 1024 * 1024 => 1,        // sizeLessThan1MiB
+        _ if size < 10 * 1024 * 1024 => 2,   // sizeLessThan10MiB
+        _ if size < 100 * 1024 * 1024 => 3,  // sizeLessThan100MiB
+        _ if size < 1024 * 1024 * 1024 => 4, // sizeLessThan1GiB
+        _ => 5,                              // sizeGreaterThan1GiB
+    }
+}
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

+pub mod bucket_stats;
 // pub mod error;
 pub mod globals;
 pub mod heal_channel;
@@ -353,11 +353,6 @@ pub const DEFAULT_OBS_TRACES_EXPORT_ENABLED: bool = true;
 /// Environment variable: RUSTFS_OBS_METRICS_EXPORT_ENABLED
 pub const DEFAULT_OBS_METRICS_EXPORT_ENABLED: bool = true;

-/// Default detailed PUT stage metrics enabled
-/// Default value: false
-/// Environment variable: RUSTFS_OBS_PUT_STAGE_METRICS_ENABLED
-pub const DEFAULT_OBS_PUT_STAGE_METRICS_ENABLED: bool = false;
-
 /// Default logs export enabled
 /// It is used to enable or disable exporting logs
 /// Default value: true
@@ -137,21 +137,6 @@ pub const DEFAULT_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED: bool = false;
 const _: () = assert!(!DEFAULT_TIER_REMOTE_VERSION_STATE_WRITE);
 const _: () = assert!(!DEFAULT_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED);

-/// Request preserving legacy per-part checksum metadata during data movement.
-///
-/// This remains ineffective until
-/// [`ENV_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED`] is also enabled.
-pub const ENV_DATA_MOVEMENT_PART_CHECKSUMS_WRITE: &str = "RUSTFS_DATA_MOVEMENT_PART_CHECKSUMS_WRITE";
-pub const DEFAULT_DATA_MOVEMENT_PART_CHECKSUMS_WRITE: bool = false;
-
-/// Operator-attested confirmation that every serving node understands the
-/// data-movement per-part checksum sidecar.
-pub const ENV_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED: &str = "RUSTFS_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED";
-pub const DEFAULT_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED: bool = false;
-
-const _: () = assert!(!DEFAULT_DATA_MOVEMENT_PART_CHECKSUMS_WRITE);
-const _: () = assert!(!DEFAULT_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED);
-
 // =============================================================================
 // Concurrent Request Fix - Timeout and Backpressure Configuration
 // =============================================================================
@@ -664,13 +649,4 @@ mod remote_version_state_tests {
            "RUSTFS_TIER_REMOTE_VERSION_STATE_FLEET_CONFIRMED"
        );
    }
-
-    #[test]
-    fn data_movement_part_checksum_gate_uses_stable_environment_names() {
-        assert_eq!(super::ENV_DATA_MOVEMENT_PART_CHECKSUMS_WRITE, "RUSTFS_DATA_MOVEMENT_PART_CHECKSUMS_WRITE");
-        assert_eq!(
-            super::ENV_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED,
-            "RUSTFS_DATA_MOVEMENT_PART_CHECKSUMS_FLEET_CONFIRMED"
-        );
-    }
 }
@@ -81,8 +81,7 @@ pub const ENV_TEST_IAM_FAIL_INIT_ATTEMPTS: &str = "RUSTFS_TEST_IAM_FAIL_INIT_ATT
 pub const ENV_TEST_IAM_RETRY_INTERVAL_MS: &str = "RUSTFS_TEST_IAM_RETRY_INTERVAL_MS";
 /// Runtime env var controlling the transition worker count.
 pub const ENV_TRANSITION_WORKERS: &str = "RUSTFS_MAX_TRANSITION_WORKERS";
-/// Runtime env var controlling the ILM expiry worker count. A set, parsable,
-/// non-zero value wins; anything else falls back to `min(cpus, 16)`.
+/// Runtime env var controlling the expiry worker count.
 pub const ENV_MAX_EXPIRY_WORKERS: &str = "RUSTFS_MAX_EXPIRY_WORKERS";
 /// Runtime env var controlling the absolute maximum transition workers.
 pub const ENV_TRANSITION_WORKERS_ABSOLUTE_MAX: &str = "RUSTFS_ABSOLUTE_MAX_WORKERS";
@@ -44,10 +44,6 @@ pub const ENV_OBS_METRICS_EXPORT_ENABLED: &str = "RUSTFS_OBS_METRICS_EXPORT_ENAB
 pub const ENV_OBS_LOGS_EXPORT_ENABLED: &str = "RUSTFS_OBS_LOGS_EXPORT_ENABLED";
 pub const ENV_OBS_PROFILING_EXPORT_ENABLED: &str = "RUSTFS_OBS_PROFILING_EXPORT_ENABLED";

-/// Enables detailed per-stage PUT metrics. Disabled by default because each
-/// PUT records multiple timers and histograms when attribution is active.
-pub const ENV_OBS_PUT_STAGE_METRICS_ENABLED: &str = "RUSTFS_OBS_PUT_STAGE_METRICS_ENABLED";
-
 pub const ENV_OBS_LOGGER_LEVEL: &str = "RUSTFS_OBS_LOGGER_LEVEL";
 pub const ENV_OBS_LOG_STDOUT_ENABLED: &str = "RUSTFS_OBS_LOG_STDOUT_ENABLED";
 pub const ENV_OBS_LOG_DIRECTORY: &str = "RUSTFS_OBS_LOG_DIRECTORY";
@@ -145,7 +141,6 @@ mod tests {
        assert_eq!(ENV_OBS_METRICS_EXPORT_ENABLED, "RUSTFS_OBS_METRICS_EXPORT_ENABLED");
        assert_eq!(ENV_OBS_LOGS_EXPORT_ENABLED, "RUSTFS_OBS_LOGS_EXPORT_ENABLED");
        assert_eq!(ENV_OBS_PROFILING_EXPORT_ENABLED, "RUSTFS_OBS_PROFILING_EXPORT_ENABLED");
-        assert_eq!(ENV_OBS_PUT_STAGE_METRICS_ENABLED, "RUSTFS_OBS_PUT_STAGE_METRICS_ENABLED");
        // Test log cleanup related env keys
        assert_eq!(ENV_OBS_LOG_MAX_TOTAL_SIZE_BYTES, "RUSTFS_OBS_LOG_MAX_TOTAL_SIZE_BYTES");
        assert_eq!(ENV_OBS_LOG_MAX_SINGLE_FILE_SIZE_BYTES, "RUSTFS_OBS_LOG_MAX_SINGLE_FILE_SIZE_BYTES");
@@ -1,612 +0,0 @@
-// Copyright 2024 RustFS Team
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-//! ILM on SSE-KMS buckets while per-key SSE authorization is enforced (backlog#1582).
-//!
-//! Per-key KMS authorization (`RUSTFS_KMS_ENFORCE_SSE_KEY_POLICY=true`) scopes the
-//! SSE-KMS data path to the requesting principal's `kms:GenerateDataKey` /
-//! `kms:Decrypt` grants. Internal callers — the lifecycle scanner's expiry deletes
-//! and the tier transition worker's reads — carry no request principal, and
-//! `authorize_sse_kms_key` (rustfs/src/storage/sse.rs) exempts a `None` principal
-//! so background maintenance keeps working on encrypted buckets.
-//!
-//! These tests pin that exemption end to end. If enforcement ever starts applying
-//! to the scanner's internal operations, expiry stops happening on SSE-KMS buckets
-//! and [`ilm_expiration_on_sse_kms_bucket_under_enforcement`] times out; if it
-//! starts applying to the transition worker or the read-through path,
-//! [`ilm_transition_on_sse_kms_bucket_under_enforcement_reads_back`] fails at the
-//! transition wait or the plaintext round-trip.
-//!
-//! The replication half of the same acceptance item lives in
-//! `crates/e2e_test/src/replication_extension_test.rs`
-//! (`test_bucket_replication_sse_kms_failure_contract`); ILM had no coverage
-//! before this file.
-//!
-//! Deployment constraint pinned by the transition test's setup: the RustFS warm
-//! backend forwards the object's stored `x-amz-server-side-encryption*` metadata
-//! as raw headers on the tier data PUT (`build_transition_put_options` +
-//! `api_put_object.rs` header mapping), so a RustFS tier target must itself have
-//! KMS enabled and hold the named key or it rejects every transition upload with
-//! 400 InvalidRequest. That rejection is independent of the enforcement switch;
-//! the cold server here therefore runs its own Local KMS with the same key id.
-
-use super::common::{LocalKMSTestEnvironment, create_key_with_specific_id};
-use crate::common::{RustFSTestEnvironment, admin_request, init_logging};
-use aws_sdk_s3::Client;
-use aws_sdk_s3::primitives::ByteStream;
-use aws_sdk_s3::types::{
-    BucketLifecycleConfiguration, ExpirationStatus, LifecycleExpiration, LifecycleRule, LifecycleRuleFilter, RestoreRequest,
-    ServerSideEncryption, ServerSideEncryptionByDefault, ServerSideEncryptionConfiguration, ServerSideEncryptionRule, Transition,
-    TransitionStorageClass,
-};
-use serde::Deserialize;
-use serial_test::serial;
-use std::time::{Duration as StdDuration, Instant};
-use tracing::info;
-
-type TestResult = Result<(), Box<dyn std::error::Error + Send + Sync>>;
-
-const SSE_KEY: &str = "kms-ilm-sse-key";
-const PAYLOAD: &[u8] = b"kms ilm sse payload: survives enforcement, expires and transitions on schedule";
-
-const EXPIRY_BUCKET: &str = "kms-ilm-expiry";
-const EXPIRE_KEY: &str = "expire/object.bin";
-const SURVIVOR_KEY: &str = "keep/object.bin";
-
-const TIER_NAME: &str = "KMSCOLD";
-const TIER_BUCKET: &str = "kms-ilm-cold-tier";
-const TIER_PREFIX: &str = "tiered";
-const TRANSITION_BUCKET: &str = "kms-ilm-transition";
-const TRANSITION_KEY: &str = "tier/object.bin";
-
-/// Generous CI safety net; with a 1s scanner cycle and 2s lifecycle days the
-/// terminal state normally lands within a few seconds.
-const ILM_DEADLINE: StdDuration = StdDuration::from_secs(90);
-
-/// Start a Local-KMS server with per-key SSE authorization enforced and the
-/// lifecycle clock accelerated.
-///
-/// KMS wiring matches `kms_authorization_negative_matrix_test.rs` (local backend,
-/// `--kms-default-key-id`, insecure dev defaults). The lifecycle env matches
-/// `reliant/lifecycle.rs::fast_lifecycle_env` plus `RUSTFS_ILM_DEBUG_DAY_SECS=2`,
-/// so a `Days=1` rule is due about two seconds after the write.
-async fn start_enforcing_ilm_server(env: &mut LocalKMSTestEnvironment) -> TestResult {
-    create_key_with_specific_id(&env.kms_keys_dir, SSE_KEY).await?;
-
-    let key_dir = env.kms_keys_dir.clone();
-    let args = vec![
-        "--kms-enable",
-        "--kms-backend",
-        "local",
-        "--kms-key-dir",
-        key_dir.as_str(),
-        "--kms-default-key-id",
-        SSE_KEY,
-    ];
-
-    let envs = [
-        ("RUSTFS_KMS_ALLOW_INSECURE_DEV_DEFAULTS", "true"),
-        ("RUSTFS_KMS_ENFORCE_SSE_KEY_POLICY", "false"),
-        ("RUSTFS_SCANNER_CYCLE", "1"),
-        ("RUSTFS_ILM_PROCESS_TIME", "1"),
-        ("RUSTFS_ILM_DEBUG_DAY_SECS", "2"),
-    ];
-
-    env.base_env.start_rustfs_server_with_env(args, &envs).await?;
-    Ok(())
-}
-
-/// Set the bucket's default encryption to SSE-KMS under [`SSE_KEY`], so plain
-/// PUTs (and internal rewrites) are encrypted without per-request SSE headers.
-async fn set_bucket_default_sse_kms(client: &Client, bucket: &str) -> TestResult {
-    let encryption_config = ServerSideEncryptionConfiguration::builder()
-        .rules(
-            ServerSideEncryptionRule::builder()
-                .apply_server_side_encryption_by_default(
-                    ServerSideEncryptionByDefault::builder()
-                        .sse_algorithm(ServerSideEncryption::AwsKms)
-                        .kms_master_key_id(SSE_KEY)
-                        .build()?,
-                )
-                .build(),
-        )
-        .build()?;
-    client
-        .put_bucket_encryption()
-        .bucket(bucket)
-        .server_side_encryption_configuration(encryption_config)
-        .send()
-        .await?;
-    Ok(())
-}
-
-/// Assert via `HeadObject` that the stored object is SSE-KMS encrypted under
-/// [`SSE_KEY`]. Without this, a bucket-default misconfiguration would let the
-/// tests pass on an unencrypted object and prove nothing about KMS.
-async fn assert_head_sse_kms(client: &Client, bucket: &str, key: &str) -> TestResult {
-    let head = client.head_object().bucket(bucket).key(key).send().await?;
-    assert_eq!(
-        head.server_side_encryption(),
-        Some(&ServerSideEncryption::AwsKms),
-        "{bucket}/{key} must be SSE-KMS encrypted via the bucket default"
-    );
-    assert_eq!(
-        head.ssekms_key_id(),
-        Some(SSE_KEY),
-        "{bucket}/{key} must be wrapped under the configured KMS key"
-    );
-    Ok(())
-}
-
-/// Returns `true` once `GET bucket/key` fails with `NoSuchKey`, `false` while it
-/// still succeeds. Any other error is surfaced. (Copied from
-/// `reliant/lifecycle.rs`; that helper is private to the reliant module.)
-async fn object_is_gone(client: &Client, bucket: &str, key: &str) -> Result<bool, Box<dyn std::error::Error + Send + Sync>> {
-    match client.get_object().bucket(bucket).key(key).send().await {
-        Ok(output) => {
-            output.body.collect().await?;
-            Ok(false)
-        }
-        Err(e) => {
-            if let Some(service_error) = e.as_service_error() {
-                if service_error.is_no_such_key() {
-                    return Ok(true);
-                }
-                return Err(format!("expected NoSuchKey, got: {e:?}").into());
-            }
-            Err(format!("expected a service error, got: {e:?}").into())
-        }
-    }
-}
-
-/// Poll until `GET bucket/key` returns `NoSuchKey`, or fail after `deadline`.
-async fn wait_for_object_expired(client: &Client, bucket: &str, key: &str, deadline: StdDuration) -> TestResult {
-    let start = Instant::now();
-    loop {
-        if object_is_gone(client, bucket, key).await? {
-            return Ok(());
-        }
-        if start.elapsed() >= deadline {
-            return Err(format!(
-                "object {bucket}/{key} was not expired by the lifecycle scanner within {}s; \
-                 SSE key-policy enforcement may have started blocking the scanner's internal deletes",
-                deadline.as_secs()
-            )
-            .into());
-        }
-        tokio::time::sleep(StdDuration::from_millis(500)).await;
-    }
-}
-
-/// Install a prefix-scoped `Days`-based expiration rule.
-async fn put_expiration_rule(client: &Client, bucket: &str, id: &str, prefix: &str, days: i32) -> TestResult {
-    let rule = LifecycleRule::builder()
-        .id(id)
-        .filter(LifecycleRuleFilter::builder().prefix(prefix).build())
-        .expiration(LifecycleExpiration::builder().days(days).build())
-        .status(ExpirationStatus::Enabled)
-        .build()?;
-    let lifecycle = BucketLifecycleConfiguration::builder().rules(rule).build()?;
-    client
-        .put_bucket_lifecycle_configuration()
-        .bucket(bucket)
-        .lifecycle_configuration(lifecycle)
-        .send()
-        .await?;
-    Ok(())
-}
-
-/// Install a prefix-scoped `Days`-based transition rule targeting [`TIER_NAME`].
-async fn put_transition_rule(client: &Client, bucket: &str, id: &str, prefix: &str, days: i32) -> TestResult {
-    let rule = LifecycleRule::builder()
-        .id(id)
-        .filter(LifecycleRuleFilter::builder().prefix(prefix).build())
-        .transitions(
-            Transition::builder()
-                .days(days)
-                .storage_class(TransitionStorageClass::from(TIER_NAME))
-                .build(),
-        )
-        .status(ExpirationStatus::Enabled)
-        .build()?;
-    let lifecycle = BucketLifecycleConfiguration::builder().rules(rule).build()?;
-    client
-        .put_bucket_lifecycle_configuration()
-        .bucket(bucket)
-        .lifecycle_configuration(lifecycle)
-        .send()
-        .await?;
-    Ok(())
-}
-
-/// Start a plain Local-KMS server (no enforcement, no lifecycle acceleration)
-/// holding [`SSE_KEY`], to serve as the cold tier target.
-///
-/// The RustFS warm backend forwards the stored SSE-KMS headers on the tier data
-/// PUT, so the target re-applies managed SSE-KMS under the named key and must
-/// be able to resolve it; without KMS it answers 400 InvalidRequest and the
-/// transition can never complete. Enforcement stays off here: the tier writes
-/// arrive under `cold`'s root credentials, and one enforcing side is enough to
-/// pin the exemption.
-async fn start_cold_tier_kms_server(env: &mut LocalKMSTestEnvironment) -> TestResult {
-    create_key_with_specific_id(&env.kms_keys_dir, SSE_KEY).await?;
-
-    let key_dir = env.kms_keys_dir.clone();
-    let args = vec![
-        "--kms-enable",
-        "--kms-backend",
-        "local",
-        "--kms-key-dir",
-        key_dir.as_str(),
-        "--kms-default-key-id",
-        SSE_KEY,
-    ];
-
-    env.base_env
-        .start_rustfs_server_with_env(args, &[("RUSTFS_KMS_ALLOW_INSECURE_DEV_DEFAULTS", "true")])
-        .await?;
-    Ok(())
-}
-
-/// The subset of the manual transition run report these tests assert on.
-///
-/// Unknown fields are ignored, so this stays compatible with report growth; the
-/// full shape is pinned by `reliant/tiering.rs`.
-#[derive(Debug, Deserialize)]
-struct ManualTransitionRunReport {
-    #[serde(default)]
-    scanned: u64,
-    #[serde(default)]
-    enqueued: u64,
-    #[serde(default)]
-    skipped_already_in_flight: u64,
-    #[serde(default)]
-    skipped_tier: u64,
-}
-
-#[derive(Debug, Deserialize)]
-struct ManualTransitionRunResponse {
-    state: String,
-    report: ManualTransitionRunReport,
-}
-
-/// One synchronous (enqueue-only) manual transition run over `bucket/prefix`,
-/// via the same admin endpoint `reliant/tiering.rs` drives.
-async fn manual_transition_run(
-    hot: &RustFSTestEnvironment,
-    bucket: &str,
-    prefix: &str,
-) -> Result<ManualTransitionRunResponse, Box<dyn std::error::Error + Send + Sync>> {
-    let bucket = urlencoding::encode(bucket);
-    let prefix = urlencoding::encode(prefix);
-    let tier = urlencoding::encode(TIER_NAME);
-    let path =
-        format!("/rustfs/admin/v3/ilm/transition/run?bucket={bucket}&prefix={prefix}&tier={tier}&dryRun=false&maxObjects=10");
-    let (status, body) = admin_request(&hot.url, http::Method::POST, &path, None, &hot.access_key, &hot.secret_key).await?;
-    if !status.is_success() {
-        return Err(format!("manual transition run failed: status={status}, body={body}").into());
-    }
-    Ok(serde_json::from_str(&body)?)
-}
-
-/// Drive manual transition runs until one reports the object as processed.
-///
-/// The `Days=1` rule becomes due about two seconds after the write
-/// (`RUSTFS_ILM_DEBUG_DAY_SECS=2`), so early runs may legitimately report the
-/// object as not yet eligible; the loop keeps running the endpoint until it
-/// either enqueues the transition, sees it already in flight (the 1s scanner
-/// backstop got there first), or finds it already on the tier.
-async fn run_manual_transition_until_processed(
-    hot: &RustFSTestEnvironment,
-    bucket: &str,
-    prefix: &str,
-    deadline: StdDuration,
-) -> TestResult {
-    let start = Instant::now();
-    loop {
-        let run = manual_transition_run(hot, bucket, prefix).await?;
-        assert_eq!(run.report.scanned, 1, "manual transition run must scan the object: {run:#?}");
-        if run.report.enqueued + run.report.skipped_already_in_flight + run.report.skipped_tier >= 1 {
-            info!(state = %run.state, report = ?run.report, "manual transition run processed the SSE-KMS object");
-            return Ok(());
-        }
-        if start.elapsed() >= deadline {
-            return Err(format!(
-                "manual transition runs never processed {bucket}/{prefix} within {}s; last report: {run:#?}",
-                deadline.as_secs()
-            )
-            .into());
-        }
-        tokio::time::sleep(StdDuration::from_millis(500)).await;
-    }
-}
-
-/// Wire `hot` -> `cold` as a `TierType::RustFS` remote tier via `AddTier`.
-///
-/// No `force`, so the server runs the real connectivity probe against `cold`
-/// (the tier bucket must already exist there). Mirrors
-/// `reliant/tiering.rs::add_rustfs_tier`, which is private to that module.
-async fn add_rustfs_tier(hot: &RustFSTestEnvironment, cold: &RustFSTestEnvironment) -> TestResult {
-    let body = serde_json::json!({
-        "type": "rustfs",
-        "rustfs": {
-            "name": TIER_NAME,
-            "endpoint": cold.url.as_str(),
-            "accessKey": cold.access_key.as_str(),
-            "secretKey": cold.secret_key.as_str(),
-            "bucket": TIER_BUCKET,
-            "prefix": TIER_PREFIX,
-            "region": "us-east-1",
-            "storageClass": ""
-        }
-    })
-    .to_string();
-
-    let (status, resp) = admin_request(
-        &hot.url,
-        http::Method::PUT,
-        "/rustfs/admin/v3/tier",
-        Some(body),
-        &hot.access_key,
-        &hot.secret_key,
-    )
-    .await?;
-    if !status.is_success() {
-        return Err(format!("AddTier(RustFS) failed: status={status}, body={resp}").into());
-    }
-    Ok(())
-}
-
-/// Poll `HEAD` until the object's storage class is the tier name (transition
-/// complete), or fail after `deadline`. (From `reliant/tiering.rs`.)
-async fn wait_for_transition(client: &Client, bucket: &str, key: &str, deadline: StdDuration) -> TestResult {
-    let start = Instant::now();
-    loop {
-        let head = client.head_object().bucket(bucket).key(key).send().await?;
-        if head.storage_class().map(|sc| sc.as_str()) == Some(TIER_NAME) {
-            return Ok(());
-        }
-        if start.elapsed() >= deadline {
-            return Err(format!(
-                "object {bucket}/{key} was not transitioned to {TIER_NAME} within {}s (storage_class={:?}); \
-                 SSE key-policy enforcement may have started blocking the transition worker's internal reads",
-                deadline.as_secs(),
-                head.storage_class()
-            )
-            .into());
-        }
-        tokio::time::sleep(StdDuration::from_millis(500)).await;
-    }
-}
-
-/// Poll `HEAD` until `x-amz-restore` reports a finished restore
-/// (`ongoing-request="false"`), or fail after `deadline`.
-async fn wait_for_restore_complete(client: &Client, bucket: &str, key: &str, deadline: StdDuration) -> TestResult {
-    let start = Instant::now();
-    loop {
-        let head = client.head_object().bucket(bucket).key(key).send().await?;
-        if head.restore().is_some_and(|r| r.contains("ongoing-request=\"false\"")) {
-            return Ok(());
-        }
-        if start.elapsed() >= deadline {
-            return Err(format!(
-                "object {bucket}/{key} restore did not complete within {}s (restore={:?}); \
-                 SSE key-policy enforcement may have started blocking the restore copy-back's internal reads",
-                deadline.as_secs(),
-                head.restore()
-            )
-            .into());
-        }
-        tokio::time::sleep(StdDuration::from_millis(500)).await;
-    }
-}
-
-/// ILM expiration keeps working on an SSE-KMS bucket while per-key SSE
-/// authorization is enforced.
-///
-/// The lifecycle scanner deletes expired objects with an internal (no-principal)
-/// identity that holds no `kms` grant. If enforcement ever starts applying to
-/// those internal deletes (or to the scanner's metadata reads) on encrypted
-/// buckets, expiry stops happening and this test times out.
-///
-/// A survivor object under a non-matching prefix isolates the rule's prefix
-/// filter as the cause of the deletion and proves the encrypted bucket stays
-/// readable end to end after the scanner has run.
-#[tokio::test]
-#[serial]
-async fn ilm_expiration_on_sse_kms_bucket_under_enforcement() -> TestResult {
-    init_logging();
-
-    let mut env = LocalKMSTestEnvironment::new().await?;
-    start_enforcing_ilm_server(&mut env).await?;
-    env.base_env.create_test_bucket(EXPIRY_BUCKET).await?;
-
-    let client = env.base_env.create_s3_client();
-    set_bucket_default_sse_kms(&client, EXPIRY_BUCKET).await?;
-
-    for key in [EXPIRE_KEY, SURVIVOR_KEY] {
-        client
-            .put_object()
-            .bucket(EXPIRY_BUCKET)
-            .key(key)
-            .body(ByteStream::from_static(PAYLOAD))
-            .send()
-            .await?;
-        assert_head_sse_kms(&client, EXPIRY_BUCKET, key).await?;
-    }
-    info!("both objects stored SSE-KMS encrypted under enforcement");
-
-    put_expiration_rule(&client, EXPIRY_BUCKET, "kms-ilm-expire", "expire/", 1).await?;
-
-    // The regression this pins: the scanner's internal delete must stay exempt
-    // from per-key SSE authorization, so the encrypted object actually expires.
-    wait_for_object_expired(&client, EXPIRY_BUCKET, EXPIRE_KEY, ILM_DEADLINE).await?;
-    info!("SSE-KMS object expired by the lifecycle scanner under enforcement");
-
-    // Negative control: same bucket, same encryption, non-matching prefix. It
-    // must survive the scanner and still decrypt for the requesting principal.
-    assert!(
-        !object_is_gone(&client, EXPIRY_BUCKET, SURVIVOR_KEY).await?,
-        "non-matching-prefix object must not be expired by a prefix-scoped rule"
-    );
-    let survivor = client.get_object().bucket(EXPIRY_BUCKET).key(SURVIVOR_KEY).send().await?;
-    assert_eq!(
-        survivor.body.collect().await?.into_bytes().as_ref(),
-        PAYLOAD,
-        "surviving SSE-KMS object must still decrypt after the scanner has run"
-    );
-
-    Ok(())
-}
-
-/// ILM transition to a remote tier keeps working on an SSE-KMS bucket while
-/// per-key SSE authorization is enforced, and the transitioned object reads
-/// back as plaintext.
-///
-/// The transition worker moves the stored (encrypted) bytes to the cold tier
-/// with an internal (no-principal) identity; the read-through `GET` then
-/// decrypts the envelope for the requesting principal. If enforcement ever
-/// starts applying to the worker's internal reads, the transition wait times
-/// out; if the stored envelope is mishandled across the tier round trip, the
-/// plaintext comparison fails.
-///
-/// The transition is driven through the manual transition-run admin endpoint
-/// (the mechanism `reliant/tiering.rs` established), so the test does not
-/// depend on scanner scheduling; the 1s scanner cycle stays on as a backstop.
-#[tokio::test]
-#[serial]
-#[ignore = "pins rustfs/rustfs#6025: GET on a transitioned managed-SSE object silently returns corrupt bytes (fails with enforcement on AND off, so it is not an authorization regression); un-ignore with the fix"]
-async fn ilm_transition_on_sse_kms_bucket_under_enforcement_reads_back() -> TestResult {
-    init_logging();
-
-    // Cold-tier server: independent credentials, its own Local KMS holding the
-    // same key id (see the module docs for why the tier target needs KMS).
-    // Started first; each server's startup cleanup only matches its own unique
-    // address and temp dir, so the two instances coexist.
-    let mut cold = LocalKMSTestEnvironment::new().await?;
-    cold.base_env.access_key = "kmscoldtieradmin".to_string();
-    cold.base_env.secret_key = "kmscoldtiersecret".to_string();
-    start_cold_tier_kms_server(&mut cold).await?;
-    let cold_client = cold.base_env.create_s3_client();
-    cold_client.create_bucket().bucket(TIER_BUCKET).send().await?;
-
-    // Hot server: Local KMS + enforcement + accelerated lifecycle clock.
-    let mut env = LocalKMSTestEnvironment::new().await?;
-    start_enforcing_ilm_server(&mut env).await?;
-    let hot_client = env.base_env.create_s3_client();
-
-    add_rustfs_tier(&env.base_env, &cold.base_env).await?;
-
-    env.base_env.create_test_bucket(TRANSITION_BUCKET).await?;
-    set_bucket_default_sse_kms(&hot_client, TRANSITION_BUCKET).await?;
-
-    hot_client
-        .put_object()
-        .bucket(TRANSITION_BUCKET)
-        .key(TRANSITION_KEY)
-        .body(ByteStream::from_static(PAYLOAD))
-        .send()
-        .await?;
-    assert_head_sse_kms(&hot_client, TRANSITION_BUCKET, TRANSITION_KEY).await?;
-    info!("object stored SSE-KMS encrypted under enforcement");
-
-    // Days=1 is due ~2s after the write with RUSTFS_ILM_DEBUG_DAY_SECS=2.
-    put_transition_rule(&hot_client, TRANSITION_BUCKET, "kms-ilm-transition", "tier/", 1).await?;
-
-    // Drive the transition deterministically via the manual run endpoint, then
-    // wait for HEAD to report the tier as the object's storage class.
-    run_manual_transition_until_processed(&env.base_env, TRANSITION_BUCKET, "tier/", ILM_DEADLINE).await?;
-    wait_for_transition(&hot_client, TRANSITION_BUCKET, TRANSITION_KEY, ILM_DEADLINE).await?;
-    info!("SSE-KMS object transitioned to the remote tier under enforcement");
-
-    let head = hot_client
-        .head_object()
-        .bucket(TRANSITION_BUCKET)
-        .key(TRANSITION_KEY)
-        .send()
-        .await?;
-    assert!(
-        head.restore().is_none(),
-        "a freshly transitioned object must not advertise x-amz-restore, got {:?}",
-        head.restore()
-    );
-
-    // The remote copy exists on the cold tier. The payload the tier holds is the
-    // hot server's stored ciphertext, wrapped once more under the cold server's
-    // own managed SSE-KMS layer (the forwarded headers re-request encryption).
-    let remote = cold_client.list_objects_v2().bucket(TIER_BUCKET).send().await?;
-    assert!(!remote.contents().is_empty(), "cold-tier bucket must hold the transitioned object's data");
-
-    // Read-through GET under enforcement must succeed (not AccessDenied) and
-    // keep advertising SSE-KMS. Its BODY is deliberately not compared here:
-    // the transitioned read path skips managed-SSE decryption — a product gap
-    // unrelated to enforcement — so a direct GET streams the stored ciphertext
-    // (`new_getobjectreader` in crates/ecstore/src/client/object_api_utils.rs
-    // hardcodes `is_encrypted = false` and never applies the
-    // `ReadTransform::Encrypted` wrapping the hot-read path builds in
-    // crates/ecstore/src/object_api/readers.rs). Plaintext recovery is pinned
-    // through restore semantics below; when the read-through gap is fixed, a
-    // byte assertion can be added here too.
-    let read_through = hot_client
-        .get_object()
-        .bucket(TRANSITION_BUCKET)
-        .key(TRANSITION_KEY)
-        .send()
-        .await?;
-    assert_eq!(
-        read_through.server_side_encryption(),
-        Some(&ServerSideEncryption::AwsKms),
-        "transitioned object must still report SSE-KMS on read-through"
-    );
-    let read_through_body = read_through.body.collect().await?.into_bytes();
-    assert_eq!(
-        read_through_body.len(),
-        PAYLOAD.len(),
-        "read-through GET must stream the object's full logical size under enforcement"
-    );
-
-    // RestoreObject copies the ciphertext back from the tier under the original
-    // envelope metadata; the restored copy is then served by the normal
-    // decrypting read path. The copy-back runs with an internal (no-principal)
-    // identity, so this also pins the exemption on the restore path. Days=300
-    // because RUSTFS_ILM_DEBUG_DAY_SECS=2 accelerates the restored copy's
-    // expiry as well (300 accelerated days == 600s of validity).
-    hot_client
-        .restore_object()
-        .bucket(TRANSITION_BUCKET)
-        .key(TRANSITION_KEY)
-        .restore_request(RestoreRequest::builder().days(300).build())
-        .send()
-        .await?;
-    wait_for_restore_complete(&hot_client, TRANSITION_BUCKET, TRANSITION_KEY, ILM_DEADLINE).await?;
-    info!("SSE-KMS object restored from the remote tier under enforcement");
-
-    // The KMS-relevant half: the restored envelope decrypts back to the exact
-    // plaintext for the requesting principal.
-    let restored = hot_client
-        .get_object()
-        .bucket(TRANSITION_BUCKET)
-        .key(TRANSITION_KEY)
-        .send()
-        .await?;
-    assert_eq!(
-        restored.server_side_encryption(),
-        Some(&ServerSideEncryption::AwsKms),
-        "restored object must still report SSE-KMS"
-    );
-    let body = restored.body.collect().await?.into_bytes();
-    assert_eq!(body.as_ref(), PAYLOAD, "restored SSE-KMS object must round-trip byte-identical plaintext");
-
-    Ok(())
-}
@@ -59,6 +59,3 @@ mod configured_roundtrip_test;

 #[cfg(test)]
 mod kms_authorization_negative_matrix_test;
-
-#[cfg(test)]
-mod kms_ilm_sse_kms_test;
@@ -2854,7 +2854,7 @@ pub(crate) mod cmptst_30 {
        result
    }

-    #[ignore = "timing-sensitive backend-pressure latency probe; run explicitly with --ignored"]
+    #[ignore]
    #[tokio::test]
    async fn regression() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
        crate::common::init_logging();
@@ -2401,20 +2401,15 @@ async fn wait_for_site_replication_info<F>(
 where
    F: Fn(&SiteReplicationInfo) -> bool,
 {
-    // 30s to match wait_for_replication_state: the three-node site tests run
-    // several full rustfs processes on one runner, so peer-state propagation
-    // can take well over 10s under CI load.
-    let deadline = tokio::time::Instant::now() + Duration::from_secs(30);
-    loop {
+    for _ in 0..40 {
        let info = site_replication_info(env).await?;
        if predicate(&info) {
            return Ok(info);
        }
-        if tokio::time::Instant::now() >= deadline {
-            return Err(format!("site replication info did not reach expected state on {}", env.address).into());
-        }
        sleep(Duration::from_millis(250)).await;
    }
+
+    Err(format!("site replication info did not reach expected state on {}", env.address).into())
 }

 async fn wait_for_site_replication_status<F>(
@@ -2425,19 +2420,15 @@ async fn wait_for_site_replication_status<F>(
 where
    F: Fn(&SRStatusInfo) -> bool,
 {
-    // Same 30s ceiling as wait_for_site_replication_info: the status probes
-    // fan out to every peer, so they see the same multi-process CI load.
-    let deadline = tokio::time::Instant::now() + Duration::from_secs(30);
-    loop {
+    for _ in 0..40 {
        let status = site_replication_status(env, query).await?;
        if predicate(&status) {
            return Ok(status);
        }
-        if tokio::time::Instant::now() >= deadline {
-            return Err(format!("site replication status did not reach expected state on {}", env.address).into());
-        }
        sleep(Duration::from_millis(250)).await;
    }
+
+    Err(format!("site replication status did not reach expected state on {}", env.address).into())
 }

 async fn wait_for_replication_reset_target<F>(
@@ -4244,49 +4235,37 @@ async fn test_bucket_replication_acceptance_matrix_local_dual_targets() -> TestR
        "tag rule with disabled delete-marker replication created a marker: {tagged_state:?}"
    );

-    // AWS S3 and MinIO both reject suspending versioning on a bucket that
-    // carries a replication configuration (InvalidBucketState): suspension
-    // would mint null versions that versioned replication can never converge.
-    let suspend_err = source_client
-        .put_bucket_versioning()
-        .bucket(source_bucket)
-        .versioning_configuration(
-            VersioningConfiguration::builder()
-                .status(BucketVersioningStatus::Suspended)
-                .build(),
-        )
-        .send()
-        .await
-        .expect_err("suspending versioning on a replication source must be rejected");
-    assert_eq!(
-        suspend_err.as_service_error().and_then(|error| error.code()),
-        Some("InvalidBucketState"),
-        "suspension on a replication source must fail with InvalidBucketState: {suspend_err:?}"
-    );
-
-    // The rejected suspension must leave the versioning + replication state
-    // fully intact: a fresh matched PUT still replicates with a real version.
-    let post_reject_put = source_client
+    set_bucket_versioning(&source_env, source_bucket, BucketVersioningStatus::Suspended).await?;
+    set_bucket_versioning(&target_env_a, target_bucket_a, BucketVersioningStatus::Suspended).await?;
+    let null_put = source_client
        .put_object()
        .bucket(source_bucket)
-        .key("prefix/after-rejected-suspend.txt")
-        .body(ByteStream::from_static(b"still replicating"))
+        .key("prefix/null.txt")
+        .body(ByteStream::from_static(b"null version"))
        .send()
        .await?;
-    let post_reject_version_id = post_reject_put
-        .version_id()
-        .ok_or("PUT after rejected suspension omitted version ID")?
-        .to_string();
-    wait_for_replication_state(
-        &target_client_a,
-        target_bucket_a,
-        "replication stopped after rejected versioning suspension",
-        |state| {
-            state
-                .iter()
-                .any(|entry| entry.key == "prefix/after-rejected-suspend.txt" && entry.version_id == post_reject_version_id)
-        },
-    )
+    assert!(null_put.version_id().is_none(), "suspended source PUT must create a null version");
+    wait_for_replication_state(&target_client_a, target_bucket_a, "null version did not replicate", |state| {
+        state
+            .iter()
+            .any(|entry| entry.key == "prefix/null.txt" && entry.version_id == "null" && !entry.delete_marker)
+    })
+    .await?;
+    let null_delete = source_client
+        .delete_object()
+        .bucket(source_bucket)
+        .key("prefix/null.txt")
+        .send()
+        .await?;
+    assert!(
+        null_delete.version_id().is_none(),
+        "suspended source DELETE must create a null delete marker"
+    );
+    wait_for_replication_state(&target_client_a, target_bucket_a, "null delete marker did not replicate", |state| {
+        state
+            .iter()
+            .any(|entry| entry.key == "prefix/null.txt" && entry.version_id == "null" && entry.delete_marker)
+    })
    .await?;

    Ok(())
@@ -32,11 +32,6 @@ workspace = true

 [features]
 default = []
-# Compiles the controlled list-objects namespace-journal chaos injector into a
-# production binary (it is always available to tests). Off by default so the
-# RUSTFS_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_* env vars cannot rewrite journal
-# state in a stock build (backlog#1832).
-list-chaos = []
 rio-v2 = ["dep:rustfs-rio-v2"]
 hotpath = [
    "hotpath/hotpath",
@@ -61,11 +61,9 @@ pub mod bucket {
                delete_manual_transition_scope_admission_if_current, load_manual_transition_job_record,
                load_manual_transition_job_record_with_etag, load_manual_transition_scope_admission,
                manual_transition_job_lease_expired, manual_transition_scope_admission_lease_expired,
-                manual_transition_scope_key, persist_manual_transition_job_progress,
-                persist_manual_transition_job_progress_if_owned, renew_manual_transition_job_lease,
-                renew_manual_transition_job_lease_if_owned, request_manual_transition_job_cancel,
-                save_manual_transition_job_record, save_manual_transition_job_record_if_current,
-                save_manual_transition_scope_admission_if_absent, update_manual_transition_job_record,
+                manual_transition_scope_key, persist_manual_transition_job_progress, renew_manual_transition_job_lease,
+                request_manual_transition_job_cancel, save_manual_transition_job_record,
+                save_manual_transition_job_record_if_current, save_manual_transition_scope_admission_if_absent,
            };
        }

@@ -346,7 +344,7 @@ pub mod disk {
    }

    pub mod error {
-        pub use crate::disk::error::{DiskError, Error, FileAccessDeniedWithContext, Result};
+        pub use crate::disk::error::{BitrotErrorType, DiskError, Error, FileAccessDeniedWithContext, Result};
    }

    pub mod error_reduce {
@@ -86,21 +86,6 @@ where
    com::save_config_with_opts(api, file, data, opts).await
 }

-pub(crate) async fn save_config_with_opts_quiet<S>(api: Arc<S>, file: &str, data: Vec<u8>, opts: &ObjectOptions) -> Result<()>
-where
-    S: ObjectIO<
-            Error = Error,
-            RangeSpec = HTTPRangeSpec,
-            HeaderMap = HeaderMap,
-            ObjectOptions = ObjectOptions,
-            ObjectInfo = ObjectInfo,
-            GetObjectReader = GetObjectReader,
-            PutObjectReader = PutObjReader,
-        >,
-{
-    com::save_config_with_opts_quiet(api, file, data, opts).await
-}
-
 pub(crate) async fn delete_config<S>(api: Arc<S>, file: &str) -> Result<()>
 where
    S: ObjectOperations<
@@ -45,104 +45,6 @@ const MANUAL_TRANSITION_JOB_LEASE_SECONDS: i128 = 60;
 const MANUAL_TRANSITION_LEGACY_SCOPE_SCAN_LIMIT: i32 = 1000;
 const MANUAL_TRANSITION_TASK_SCAN_LIMIT: i32 = 1000;
 const MANUAL_TRANSITION_WORKER_RESULT_SCAN_LIMIT: i32 = 1000;
-const MANUAL_TRANSITION_JOB_CAS_RETRIES: usize = 4;
-
-#[cfg(test)]
-struct ManualTransitionJobCasBarrierState {
-    job_id: Uuid,
-    paused: std::sync::atomic::AtomicBool,
-    arrived: tokio::sync::Notify,
-    release: tokio::sync::Semaphore,
-}
-
-#[cfg(test)]
-pub(crate) struct ManualTransitionJobCasBarrier {
-    state: Arc<ManualTransitionJobCasBarrierState>,
-}
-
-#[cfg(test)]
-static MANUAL_TRANSITION_JOB_CAS_BARRIER: std::sync::OnceLock<std::sync::Mutex<Option<Arc<ManualTransitionJobCasBarrierState>>>> =
-    std::sync::OnceLock::new();
-
-#[cfg(test)]
-impl ManualTransitionJobCasBarrier {
-    pub(crate) fn install(job_id: Uuid) -> Self {
-        let state = Arc::new(ManualTransitionJobCasBarrierState {
-            job_id,
-            paused: std::sync::atomic::AtomicBool::new(false),
-            arrived: tokio::sync::Notify::new(),
-            release: tokio::sync::Semaphore::new(0),
-        });
-        let mut slot = MANUAL_TRANSITION_JOB_CAS_BARRIER
-            .get_or_init(|| std::sync::Mutex::new(None))
-            .lock()
-            .expect("manual transition progress CAS barrier mutex should not poison");
-        assert!(
-            slot.is_none(),
-            "manual transition job CAS barrier must be installed by one test at a time"
-        );
-        *slot = Some(Arc::clone(&state));
-        drop(slot);
-        Self { state }
-    }
-
-    pub(crate) async fn wait_until_paused(&self) {
-        tokio::time::timeout(std::time::Duration::from_secs(30), async {
-            loop {
-                let arrived = self.state.arrived.notified();
-                if self.state.paused.load(std::sync::atomic::Ordering::Acquire) {
-                    return;
-                }
-                arrived.await;
-            }
-        })
-        .await
-        .expect("manual transition job update should reach the deterministic CAS barrier");
-    }
-
-    pub(crate) fn release(&self) {
-        self.state.release.add_permits(1);
-    }
-}
-
-#[cfg(test)]
-impl Drop for ManualTransitionJobCasBarrier {
-    fn drop(&mut self) {
-        self.release();
-        let mut slot = MANUAL_TRANSITION_JOB_CAS_BARRIER
-            .get_or_init(|| std::sync::Mutex::new(None))
-            .lock()
-            .expect("manual transition progress CAS barrier mutex should not poison");
-        if slot.as_ref().is_some_and(|state| Arc::ptr_eq(state, &self.state)) {
-            *slot = None;
-        }
-    }
-}
-
-#[cfg(test)]
-async fn pause_manual_transition_job_before_first_cas(job_id: Uuid) {
-    let barrier = MANUAL_TRANSITION_JOB_CAS_BARRIER
-        .get_or_init(|| std::sync::Mutex::new(None))
-        .lock()
-        .expect("manual transition progress CAS barrier mutex should not poison")
-        .as_ref()
-        .filter(|barrier| barrier.job_id == job_id)
-        .cloned();
-    if let Some(barrier) = barrier
-        && barrier
-            .paused
-            .compare_exchange(false, true, std::sync::atomic::Ordering::AcqRel, std::sync::atomic::Ordering::Acquire)
-            .is_ok()
-    {
-        barrier.arrived.notify_one();
-        barrier
-            .release
-            .acquire()
-            .await
-            .expect("manual transition job CAS barrier should remain open")
-            .forget();
-    }
-}

 fn is_false(value: &bool) -> bool {
    !*value
@@ -246,6 +148,7 @@ impl ManualTransitionJobRecord {

    pub fn fail(&mut self, error: impl Into<String>) {
        self.state = ManualTransitionJobState::Failed;
+        self.report.tier_failure = self.report.tier_failure.saturating_add(1);
        self.error = Some(error.into());
        self.mark_updated_terminal();
    }
@@ -1137,7 +1040,7 @@ pub async fn save_manual_transition_job_record_if_current(
    }
    let object = manual_transition_job_record_object_name(job.job_id).map_err(manual_transition_job_store_error)?;
    let data = job.encode().map_err(manual_transition_job_store_error)?;
-    config_boundary::save_config_with_opts_quiet(
+    config_boundary::save_config_with_opts(
        api,
        &object,
        data,
@@ -1153,54 +1056,6 @@ pub async fn save_manual_transition_job_record_if_current(
    .await
 }

-/// Applies a job-record mutation with optimistic concurrency control.
-///
-/// The mutation returns whether the record needs to be persisted. When a lease
-/// is supplied, ownership is checked again after every conflicting write.
-pub async fn update_manual_transition_job_record<F>(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Option<Uuid>,
-    update: F,
-) -> EcstoreResult<ManualTransitionJobRecord>
-where
-    F: FnMut(&mut ManualTransitionJobRecord) -> bool,
-{
-    update_manual_transition_job_record_from(api, job_id, expected_lease_id, None, update).await
-}
-
-async fn update_manual_transition_job_record_from<F>(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Option<Uuid>,
-    mut current: Option<(ManualTransitionJobRecord, String)>,
-    mut update: F,
-) -> EcstoreResult<ManualTransitionJobRecord>
-where
-    F: FnMut(&mut ManualTransitionJobRecord) -> bool,
-{
-    for _ in 0..MANUAL_TRANSITION_JOB_CAS_RETRIES {
-        let (mut record, etag) = match current.take() {
-            Some(current) => current,
-            None => load_manual_transition_job_record_with_etag(api.clone(), job_id).await?,
-        };
-        if expected_lease_id.is_some_and(|lease_id| record.lease_id != lease_id) {
-            return Err(Error::PreconditionFailed);
-        }
-        if !update(&mut record) {
-            return Ok(record);
-        }
-        #[cfg(test)]
-        pause_manual_transition_job_before_first_cas(job_id).await;
-        match save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await {
-            Ok(()) => return Ok(record),
-            Err(Error::PreconditionFailed) => continue,
-            Err(err) => return Err(err),
-        }
-    }
-    Err(Error::PreconditionFailed)
-}
-
 pub(crate) async fn save_manual_transition_worker_result_if_absent(
    api: Arc<ECStore>,
    record: &ManualTransitionWorkerResultRecord,
@@ -1459,113 +1314,99 @@ pub async fn reconcile_manual_transition_worker_results(
    api: Arc<ECStore>,
    job_id: Uuid,
    queue_snapshot: ManualTransitionQueueSnapshot,
-) -> EcstoreResult<ManualTransitionJobRecord> {
-    reconcile_manual_transition_worker_results_inner(api, job_id, None, queue_snapshot, false).await
-}
-
-pub(crate) async fn reconcile_manual_transition_worker_results_if_owned(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Uuid,
-    queue_snapshot: ManualTransitionQueueSnapshot,
-) -> EcstoreResult<ManualTransitionJobRecord> {
-    reconcile_manual_transition_worker_results_inner(api, job_id, Some(expected_lease_id), queue_snapshot, false).await
-}
-
-async fn reconcile_manual_transition_worker_results_inner(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Option<Uuid>,
-    queue_snapshot: ManualTransitionQueueSnapshot,
-    mark_missing_results_unknown: bool,
 ) -> EcstoreResult<ManualTransitionJobRecord> {
    let task_stats = match scan_manual_transition_task_journal(api.clone(), job_id).await? {
        ManualTransitionTaskJournal::Stats(stats) => stats,
        ManualTransitionTaskJournal::Corrupt(error) => {
-            return mark_manual_transition_job_unknown_for_task_journal_error(
-                api,
-                job_id,
-                expected_lease_id,
-                error,
-                queue_snapshot,
-            )
-            .await;
+            return mark_manual_transition_job_unknown_for_task_journal_error(api, job_id, error, queue_snapshot).await;
        }
    };
    let stats = match scan_manual_transition_worker_result_journal(api.clone(), job_id).await? {
        ManualTransitionWorkerResultJournal::Stats(stats) => stats,
        ManualTransitionWorkerResultJournal::Corrupt(error) => {
-            return mark_manual_transition_job_unknown_for_worker_result_journal_error(
-                api,
-                job_id,
-                expected_lease_id,
-                error,
-                queue_snapshot,
-            )
-            .await;
+            return mark_manual_transition_job_unknown_for_worker_result_journal_error(api, job_id, error, queue_snapshot).await;
        }
    };
-    let mut changed = false;
-    let record = update_manual_transition_job_record(api.clone(), job_id, expected_lease_id, |record| {
-        let counts_changed = record.apply_worker_result_counts(
+    for _ in 0..4 {
+        let (mut record, etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
+        let changed = record.apply_worker_result_counts(
            stats.stats.completed,
            stats.stats.failed,
            &stats.stats.tier_failure_by_reason,
            task_stats.queued,
            queue_snapshot,
        );
-        let became_unknown = mark_missing_results_unknown && record.mark_unknown_if_worker_results_lost(queue_snapshot);
-        changed = counts_changed || became_unknown;
-        changed
-    })
-    .await?;
-    if !changed {
-        return Ok(record);
+        if !changed {
+            return Ok(record);
+        }
+        match save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await {
+            Ok(()) => {
+                if record.is_terminal() {
+                    delete_manual_transition_scope_admission_if_current(
+                        api.clone(),
+                        &record.scope_key,
+                        record.job_id,
+                        record.lease_id,
+                    )
+                    .await?;
+                } else {
+                    renew_manual_transition_scope_admission_from_job(api, &record).await?;
+                }
+                return Ok(record);
+            }
+            Err(Error::PreconditionFailed) => continue,
+            Err(err) => return Err(err),
+        }
    }
-    if record.is_terminal() {
-        delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id).await?;
-    } else {
-        renew_manual_transition_scope_admission_from_job(api, &record).await?;
-    }
-    Ok(record)
+    Err(Error::PreconditionFailed)
 }

 async fn mark_manual_transition_job_unknown_for_task_journal_error(
    api: Arc<ECStore>,
    job_id: Uuid,
-    expected_lease_id: Option<Uuid>,
    error: String,
    queue_snapshot: ManualTransitionQueueSnapshot,
 ) -> EcstoreResult<ManualTransitionJobRecord> {
-    let mut changed = false;
-    let record = update_manual_transition_job_record(api.clone(), job_id, expected_lease_id, |record| {
-        changed = record.mark_unknown_for_task_journal_error(error.clone(), queue_snapshot);
-        changed
-    })
-    .await?;
-    if changed && record.is_terminal() {
-        delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id).await?;
+    for _ in 0..4 {
+        let (mut record, etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
+        if !record.mark_unknown_for_task_journal_error(error.clone(), queue_snapshot) {
+            return Ok(record);
+        }
+        match save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await {
+            Ok(()) => {
+                delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id)
+                    .await?;
+                return Ok(record);
+            }
+            Err(Error::PreconditionFailed) => continue,
+            Err(err) => return Err(err),
+        }
    }
-    Ok(record)
+    Err(Error::PreconditionFailed)
 }

 async fn mark_manual_transition_job_unknown_for_worker_result_journal_error(
    api: Arc<ECStore>,
    job_id: Uuid,
-    expected_lease_id: Option<Uuid>,
    error: String,
    queue_snapshot: ManualTransitionQueueSnapshot,
 ) -> EcstoreResult<ManualTransitionJobRecord> {
-    let mut changed = false;
-    let record = update_manual_transition_job_record(api.clone(), job_id, expected_lease_id, |record| {
-        changed = record.mark_unknown_for_worker_result_journal_error(error.clone(), queue_snapshot);
-        changed
-    })
-    .await?;
-    if changed && record.is_terminal() {
-        delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id).await?;
+    for _ in 0..4 {
+        let (mut record, etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
+        if !record.mark_unknown_for_worker_result_journal_error(error.clone(), queue_snapshot) {
+            return Ok(record);
+        }
+        match save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await {
+            Ok(()) => {
+                delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id)
+                    .await?;
+                return Ok(record);
+            }
+            Err(Error::PreconditionFailed) => continue,
+            Err(err) => return Err(err),
+        }
    }
-    Ok(record)
+    Err(Error::PreconditionFailed)
 }

 pub async fn save_manual_transition_scope_admission_if_absent(
@@ -1762,14 +1603,19 @@ async fn find_active_legacy_manual_transition_scope_conflict(
 }

 pub async fn request_manual_transition_job_cancel(api: Arc<ECStore>, job_id: Uuid) -> EcstoreResult<ManualTransitionJobRecord> {
-    update_manual_transition_job_record(api, job_id, None, |record| {
+    for _ in 0..4 {
+        let (mut record, etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
        if record.is_terminal() || record.cancel_requested {
-            return false;
+            return Ok(record);
        }
        record.mark_cancel_requested();
-        true
-    })
-    .await
+        match save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await {
+            Ok(()) => return Ok(record),
+            Err(Error::PreconditionFailed) => continue,
+            Err(err) => return Err(err),
+        }
+    }
+    Err(Error::PreconditionFailed)
 }

 pub async fn persist_manual_transition_job_progress(
@@ -1778,39 +1624,10 @@ pub async fn persist_manual_transition_job_progress(
    report: &ManualTransitionRunReport,
    queue_snapshot: ManualTransitionQueueSnapshot,
 ) -> EcstoreResult<ManualTransitionJobRecord> {
-    let current = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
-    persist_manual_transition_job_progress_inner(api, job_id, current.0.lease_id, Some(current), report, queue_snapshot).await
-}
-
-pub async fn persist_manual_transition_job_progress_if_owned(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Uuid,
-    report: &ManualTransitionRunReport,
-    queue_snapshot: ManualTransitionQueueSnapshot,
-) -> EcstoreResult<ManualTransitionJobRecord> {
-    persist_manual_transition_job_progress_inner(api, job_id, expected_lease_id, None, report, queue_snapshot).await
-}
-
-async fn persist_manual_transition_job_progress_inner(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Uuid,
-    current: Option<(ManualTransitionJobRecord, String)>,
-    report: &ManualTransitionRunReport,
-    queue_snapshot: ManualTransitionQueueSnapshot,
-) -> EcstoreResult<ManualTransitionJobRecord> {
-    let record = update_manual_transition_job_record_from(api.clone(), job_id, Some(expected_lease_id), current, |record| {
-        if record.state != ManualTransitionJobState::Running {
-            return false;
-        }
-        record.update_running_progress(report.clone(), queue_snapshot);
-        true
-    })
-    .await?;
-    if record.state == ManualTransitionJobState::Running {
-        renew_manual_transition_scope_admission_from_job(api, &record).await?;
-    }
+    let (mut record, etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
+    record.update_running_progress(report.clone(), queue_snapshot);
+    save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await?;
+    renew_manual_transition_scope_admission_from_job(api, &record).await?;
    Ok(record)
 }

@@ -1844,58 +1661,25 @@ pub async fn renew_manual_transition_job_lease(
    job_id: Uuid,
    queue_snapshot: ManualTransitionQueueSnapshot,
 ) -> EcstoreResult<ManualTransitionJobRecord> {
-    let current = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
-    renew_manual_transition_job_lease_inner(api, job_id, current.0.lease_id, Some(current), queue_snapshot).await
-}
-
-pub async fn renew_manual_transition_job_lease_if_owned(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Uuid,
-    queue_snapshot: ManualTransitionQueueSnapshot,
-) -> EcstoreResult<ManualTransitionJobRecord> {
-    renew_manual_transition_job_lease_inner(api, job_id, expected_lease_id, None, queue_snapshot).await
-}
-
-async fn renew_manual_transition_job_lease_inner(
-    api: Arc<ECStore>,
-    job_id: Uuid,
-    expected_lease_id: Uuid,
-    current: Option<(ManualTransitionJobRecord, String)>,
-    queue_snapshot: ManualTransitionQueueSnapshot,
-) -> EcstoreResult<ManualTransitionJobRecord> {
-    let (current, current_etag) = match current {
-        Some(current) => current,
-        None => load_manual_transition_job_record_with_etag(api.clone(), job_id).await?,
-    };
-    if current.lease_id != expected_lease_id {
-        return Err(Error::PreconditionFailed);
-    }
-    if current.state != ManualTransitionJobState::Running {
-        return Ok(current);
-    }
-    if current.scan_completed && queue_snapshot.queued == 0 && queue_snapshot.active == 0 {
-        return reconcile_manual_transition_worker_results_inner(api, job_id, Some(expected_lease_id), queue_snapshot, true)
-            .await;
-    }
-    let record = update_manual_transition_job_record_from(
-        api.clone(),
-        job_id,
-        Some(expected_lease_id),
-        Some((current, current_etag)),
-        |record| {
-            if record.state != ManualTransitionJobState::Running {
-                return false;
+    let (mut record, mut etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
+    if record.state == ManualTransitionJobState::Running {
+        if record.scan_completed && queue_snapshot.queued == 0 && queue_snapshot.active == 0 {
+            record = reconcile_manual_transition_worker_results(api.clone(), job_id, queue_snapshot).await?;
+            if record.is_terminal() || !record.report.worker_transition_pending() {
+                return Ok(record);
            }
+            (record, etag) = load_manual_transition_job_record_with_etag(api.clone(), job_id).await?;
+        }
+        let became_terminal = record.mark_unknown_if_worker_results_lost(queue_snapshot);
+        if !became_terminal {
            record.renew_lease(queue_snapshot);
-            true
-        },
-    )
-    .await?;
-    if record.is_terminal() {
-        delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id).await?;
-    } else if record.state == ManualTransitionJobState::Running {
-        renew_manual_transition_scope_admission_from_job(api, &record).await?;
+        }
+        save_manual_transition_job_record_if_current(api.clone(), &record, &etag).await?;
+        if became_terminal {
+            delete_manual_transition_scope_admission_if_current(api, &record.scope_key, record.job_id, record.lease_id).await?;
+        } else {
+            renew_manual_transition_scope_admission_from_job(api, &record).await?;
+        }
    }
    Ok(record)
 }
@@ -1904,31 +1688,15 @@ async fn renew_manual_transition_scope_admission_from_job(
    api: Arc<ECStore>,
    record: &ManualTransitionJobRecord,
 ) -> EcstoreResult<()> {
-    for _ in 0..MANUAL_TRANSITION_JOB_CAS_RETRIES {
-        let (admission, admission_etag) =
-            match load_manual_transition_scope_admission_with_etag(api.clone(), &record.scope_key).await {
-                Ok(admission) => admission,
-                Err(Error::ConfigNotFound) => return Ok(()),
-                Err(err) => return Err(err),
-            };
-        if admission.job_id != record.job_id || admission.lease_id != record.lease_id {
-            return Err(Error::PreconditionFailed);
-        }
-        let mut renewed_admission = ManualTransitionScopeAdmission::from_job(record);
-        renewed_admission.lease_expires_at_unix_nanos = renewed_admission
-            .lease_expires_at_unix_nanos
-            .max(admission.lease_expires_at_unix_nanos);
-        renewed_admission.updated_at_unix_nanos = renewed_admission.updated_at_unix_nanos.max(admission.updated_at_unix_nanos);
-        if renewed_admission == admission {
-            return Ok(());
-        }
-        match save_manual_transition_scope_admission_if_current(api.clone(), &renewed_admission, &admission_etag).await {
-            Ok(()) => return Ok(()),
-            Err(Error::PreconditionFailed) => continue,
-            Err(err) => return Err(err),
-        }
+    if let Ok((admission, admission_etag)) =
+        load_manual_transition_scope_admission_with_etag(api.clone(), &record.scope_key).await
+        && admission.job_id == record.job_id
+        && admission.lease_id == record.lease_id
+    {
+        let renewed_admission = ManualTransitionScopeAdmission::from_job(record);
+        save_manual_transition_scope_admission_if_current(api, &renewed_admission, &admission_etag).await?;
    }
-    Err(Error::PreconditionFailed)
+    Ok(())
 }

 pub async fn delete_manual_transition_scope_admission_if_current(
@@ -2618,14 +2386,14 @@ mod tests {
    }

    #[test]
-    fn manual_transition_job_record_control_plane_failure_does_not_count_tier_failure() {
+    fn manual_transition_job_record_failure_counts_tier_failure() {
        let options = ManualTransitionRunOptions::default();
        let mut record = ManualTransitionJobRecord::new(Uuid::new_v4(), "bucket", &options, TEST_OWNER);

        record.fail("missing tier");

        assert_eq!(record.state, ManualTransitionJobState::Failed);
-        assert_eq!(record.report.tier_failure, 0);
+        assert_eq!(record.report.tier_failure, 1);
        assert_eq!(record.error.as_deref(), Some("missing tier"));
    }

@@ -27,24 +27,12 @@ use crate::client::utils::base64_decode;
 use crate::client::utils::base64_encode;
 use crate::client::{api_put_object::PutObjectOptions, api_s3_datatypes::ObjectPart};
 use crate::{disk::DiskAPI, object_api::GetObjectReader};
-// s3s::header has no CRC64NVME constant yet; the canonical RustFS copy lives
-// in rustfs-utils' headers module.
-use rustfs_utils::http::headers::AMZ_CHECKSUM_CRC64NVME;
 use s3s::header::{
    X_AMZ_CHECKSUM_ALGORITHM, X_AMZ_CHECKSUM_CRC32, X_AMZ_CHECKSUM_CRC32C, X_AMZ_CHECKSUM_SHA1, X_AMZ_CHECKSUM_SHA256,
 };

 use enumset::{EnumSet, EnumSetType, enum_set};

-/// One of three deliberately separate checksum registries (backlog#1833):
-/// this enum is the MinIO-port client's wire vocabulary and stops at the
-/// standard S3 set (CRC64NVME is its newest member; the RustFS extensions do
-/// not exist on this client path). The streaming-hash registry lives in
-/// `rustfs_checksums::ChecksumAlgorithm` (crates/checksums/src/lib.rs) and
-/// the on-disk xl.meta bitset in `rustfs_rio::ChecksumType`
-/// (crates/rio/src/checksum.rs, varint bits are append-only). When adding an
-/// algorithm, extend all three (or record why not) — they do not derive from
-/// each other.
 #[derive(Debug, EnumSetType, Default)]
 #[enumset(repr = "u8")]
 pub enum ChecksumMode {
@@ -69,6 +57,8 @@ lazy_static! {
    static ref C_ChecksumFullObjectCRC32C: EnumSet<ChecksumMode> =
        enum_set!(ChecksumMode::ChecksumCRC32C | ChecksumMode::ChecksumFullObject);
 }
+const AMZ_CHECKSUM_CRC64NVME: &str = "x-amz-checksum-crc64nvme";
+
 impl ChecksumMode {
    //pub const CRC64_NVME_POLYNOMIAL: i64 = 0xad93d23594c93659;

@@ -31,7 +31,7 @@ use rustfs_config::{
    DEFAULT_INTERNODE_DATA_TRANSPORT, ENV_RUSTFS_INTERNODE_DATA_TRANSPORT, INTERNODE_DATA_TRANSPORT_TCP,
    KNOWN_INTERNODE_DATA_TRANSPORT_BACKENDS,
 };
-use rustfs_rio::{ChunkReaderBox, HttpChunkReader, HttpReader, HttpWriter};
+use rustfs_rio::{HttpReader, HttpWriter};
 use sha2::{Digest, Sha256};
 use std::collections::HashMap;
 use std::future::Future;
@@ -221,11 +221,6 @@ pub struct NsScannerCapabilityRequest {
 #[async_trait]
 pub trait InternodeDataTransport: Send + Sync + std::fmt::Debug {
    async fn open_read(&self, request: ReadStreamRequest) -> Result<FileReader>;
-    /// Opens an owned-chunk stream when this transport can retain receive-buffer
-    /// ownership. `None` preserves the established `open_read` fallback.
-    async fn open_read_chunks(&self, _request: ReadStreamRequest) -> Result<Option<ChunkReaderBox>> {
-        Ok(None)
-    }
    async fn open_write(&self, request: WriteStreamRequest) -> Result<FileWriter>;
    async fn open_walk_dir(&self, request: WalkDirStreamRequest) -> Result<FileReader>;
    async fn open_ns_scanner(&self, _request: NsScannerStreamRequest) -> Result<FileReader> {
@@ -252,15 +247,6 @@ impl InternodeDataTransport for TcpHttpInternodeDataTransport {
        ))
    }

-    async fn open_read_chunks(&self, request: ReadStreamRequest) -> Result<Option<ChunkReaderBox>> {
-        let url = build_read_file_stream_url(&request);
-        let mut headers = json_headers();
-        build_auth_headers(&url, &Method::GET, &mut headers)?;
-        Ok(Some(Box::new(
-            HttpChunkReader::new_with_stall_timeout(url, Method::GET, headers, None, request.stall_timeout).await?,
-        )))
-    }
-
    async fn open_write(&self, request: WriteStreamRequest) -> Result<FileWriter> {
        let server_epoch = self.put_file_auth_capability(&request.endpoint).await?;
        let nonce = server_epoch.map(|_| Uuid::new_v4());
@@ -522,33 +522,6 @@ impl RemoteDisk {
        }
    }

-    async fn open_read_chunks_with_retry(&self, request: ReadStreamRequest) -> Result<Option<rustfs_rio::ChunkReaderBox>> {
-        let mut attempt = 1;
-        let mut last_retry_classification = None;
-        loop {
-            match self.data_transport.open_read_chunks(request.clone()).await {
-                Ok(reader) => {
-                    if attempt > 1
-                        && let Some(classification) = last_retry_classification
-                    {
-                        crate::cluster::rpc::runtime_sources::record_remote_disk_open_read_retry_success(classification);
-                    }
-                    return Ok(reader);
-                }
-                Err(err) if attempt < REMOTE_DISK_OPEN_READ_MAX_ATTEMPTS && Self::is_retryable_open_read_error(&err) => {
-                    if let Some(classification) = err.internode_http_error_kind() {
-                        let classification = classification.metric_label();
-                        crate::cluster::rpc::runtime_sources::record_remote_disk_open_read_retry(classification);
-                        last_retry_classification = Some(classification);
-                    }
-                    tokio::time::sleep(REMOTE_DISK_OPEN_READ_RETRY_BACKOFF).await;
-                    attempt += 1;
-                }
-                Err(err) => return Err(err),
-            }
-        }
-    }
-
    pub fn record_capacity_probe(&self, total: u64, used: u64, free: u64) {
        self.health.record_capacity_probe(total, used, free);
    }
@@ -873,49 +846,31 @@ impl RemoteDisk {
    /// default to 1 (see [`internode_idempotent_read_retries`]). MUST NOT be used for write/lock
    /// RPCs — those must never auto-retry (quorum/idempotency safety). The `operation` closure is
    /// re-invoked per attempt, so it must be `Fn` (rebuild the request from borrowed inputs, do not
-    /// move captured state out). Attempts and backoff share one total timeout budget.
+    /// move captured state out).
    async fn execute_read_with_retry<T, F, Fut>(&self, op: &'static str, operation: F, timeout_duration: Duration) -> Result<T>
    where
        F: Fn() -> Fut,
        Fut: std::future::Future<Output = Result<T>>,
    {
-        let deadline = (!timeout_duration.is_zero()).then(|| {
-            time::Instant::now()
-                .checked_add(timeout_duration)
-                .unwrap_or_else(|| time::sleep(timeout_duration).deadline())
-        });
        let max_retries = internode_idempotent_read_retries();
        let mut attempt = 0usize;
        loop {
-            let attempt_timeout = deadline
-                .map(|deadline| deadline.saturating_duration_since(time::Instant::now()))
-                .unwrap_or(Duration::ZERO);
-            if deadline.is_some() && attempt_timeout.is_zero() {
-                self.record_timeout(op, timeout_duration);
-                return Err(DiskError::Timeout);
-            }
-
+            // Only the final attempt marks the disk faulty / evicts the channel. Earlier retries
+            // ignore the failure, so a transient error cannot flip the disk into a faulty
+            // short-circuit (which would defeat the retry) or over-count failures.
            let health_action = if attempt >= max_retries {
                FailureHealthAction::MarkFailure
            } else {
                FailureHealthAction::IgnoreFailure
            };
            match self
-                .execute_with_timeout_for_op_and_health_action(op, &operation, attempt_timeout, health_action)
+                .execute_with_timeout_for_op_and_health_action(op, &operation, timeout_duration, health_action)
                .await
            {
                Err(err) if attempt < max_retries && is_network_like_disk_error(&err) => {
-                    if matches!(err, DiskError::Timeout) && deadline.is_some_and(|deadline| time::Instant::now() >= deadline) {
-                        self.mark_faulty("read_operation_deadline");
-                        return Err(err);
-                    }
                    attempt += 1;
                    let backoff = REMOTE_DISK_READ_RETRY_BASE_BACKOFF
                        .saturating_mul(1u32 << u32::try_from(attempt - 1).unwrap_or(4).min(4));
-                    if deadline.is_some_and(|deadline| deadline.saturating_duration_since(time::Instant::now()) <= backoff) {
-                        attempt = max_retries;
-                        continue;
-                    }
                    debug!(
                        endpoint = %self.endpoint,
                        addr = %self.addr,
@@ -923,17 +878,7 @@ impl RemoteDisk {
                        attempt,
                        "retrying idempotent read-only RPC after transient network error"
                    );
-                    if let Some(deadline) = deadline {
-                        if time::timeout_at(deadline, time::sleep(backoff)).await.is_err() {
-                            self.record_timeout(op, timeout_duration);
-                            return Err(DiskError::Timeout);
-                        }
-                    } else {
-                        time::sleep(backoff).await;
-                    }
-                    if self.health.is_faulty() {
-                        return Err(DiskError::FaultyDisk);
-                    }
+                    tokio::time::sleep(backoff).await;
                }
                other => return other,
            }
@@ -1012,35 +957,32 @@ impl RemoteDisk {
                operation_result
            }
            Err(_) => {
-                self.record_timeout(op, timeout_duration);
+                // Timeout occurred, mark disk as potentially faulty
+                counter!(
+                    "rustfs_drive_op_timeout_total",
+                    "endpoint" => self.endpoint.to_string(),
+                    "op" => op.to_string()
+                )
+                .increment(1);
                if failure_health_action == FailureHealthAction::MarkFailure {
                    self.mark_faulty_and_evict("operation_timeout").await;
                }
+                warn!(
+                    event = EVENT_REMOTE_DISK_RPC,
+                    component = LOG_COMPONENT_ECSTORE,
+                    subsystem = LOG_SUBSYSTEM_REMOTE_DISK,
+                    endpoint = %self.endpoint,
+                    addr = %self.addr,
+                    op,
+                    timeout_ms = timeout_duration.as_millis(),
+                    state = "timeout",
+                    "Remote disk operation timed out"
+                );
                Err(DiskError::Timeout)
            }
        }
    }

-    fn record_timeout(&self, op: &'static str, timeout_duration: Duration) {
-        counter!(
-            "rustfs_drive_op_timeout_total",
-            "endpoint" => self.endpoint.to_string(),
-            "op" => op.to_string()
-        )
-        .increment(1);
-        warn!(
-            event = EVENT_REMOTE_DISK_RPC,
-            component = LOG_COMPONENT_ECSTORE,
-            subsystem = LOG_SUBSYSTEM_REMOTE_DISK,
-            endpoint = %self.endpoint,
-            addr = %self.addr,
-            op,
-            timeout_ms = timeout_duration.as_millis(),
-            state = "timeout",
-            "Remote disk operation timed out"
-        );
-    }
-
    async fn handle_network_like_error<T>(
        &self,
        op: &'static str,
@@ -1074,7 +1016,7 @@ impl RemoteDisk {
        }
    }

-    fn mark_faulty(&self, reason: &'static str) -> bool {
+    async fn mark_faulty_and_evict(&self, reason: &'static str) {
        let previous_state = self.runtime_state();
        let transitioned_to_offline = self.mark_suspect_or_offline(reason);
        let state = self.runtime_state();
@@ -1111,12 +1053,6 @@ impl RemoteDisk {
                    "Remote disk marked suspect"
                );
            }
-        }
-        state != previous_state
-    }
-
-    async fn mark_faulty_and_evict(&self, reason: &'static str) {
-        if self.mark_faulty(reason) {
            counter!(
                "rustfs_drive_connection_evict_total",
                "endpoint" => self.endpoint.to_string(),
@@ -2132,7 +2068,7 @@ impl DiskAPI for RemoteDisk {

                Ok(file_info)
            },
-            get_drive_metadata_timeout(),
+            get_max_timeout_duration(),
        )
        .await
    }
@@ -2481,30 +2417,6 @@ impl DiskAPI for RemoteDisk {
        .await
    }

-    async fn read_file_stream_chunks(
-        &self,
-        volume: &str,
-        path: &str,
-        offset: usize,
-        length: usize,
-    ) -> Result<Option<rustfs_rio::ChunkReaderBox>> {
-        if self.health.is_faulty() {
-            return Err(DiskError::FaultyDisk);
-        }
-        let disk = self.disk_ref().await;
-        let stall_timeout = get_object_disk_read_timeout();
-        self.open_read_chunks_with_retry(ReadStreamRequest {
-            endpoint: self.endpoint.grid_host(),
-            disk,
-            volume: volume.to_string(),
-            path: path.to_string(),
-            offset,
-            length,
-            stall_timeout: (!stall_timeout.is_zero()).then_some(stall_timeout),
-        })
-        .await
-    }
-
    /// Buffered read for remote disks.
    /// The transport stream is collected into owned Bytes for caller sharing.
    #[tracing::instrument(level = "trace", skip_all)]
@@ -5182,452 +5094,6 @@ mod tests {
        );
    }

-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_reset_during_backoff_preserves_recovery() {
-        let remote_disk = Arc::new(new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await);
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let first_attempt = Arc::new(tokio::sync::Notify::new());
-        let started = time::Instant::now();
-
-        let task_disk = Arc::clone(&remote_disk);
-        let task_attempts = Arc::clone(&attempts);
-        let task_first_attempt = Arc::clone(&first_attempt);
-        let task = tokio::spawn(async move {
-            task_disk
-                .execute_read_with_retry(
-                    "read_version",
-                    move || {
-                        let attempt = task_attempts.fetch_add(1, Ordering::SeqCst);
-                        let first_attempt = Arc::clone(&task_first_attempt);
-                        async move {
-                            if attempt == 0 {
-                                time::sleep(Duration::from_millis(20)).await;
-                                first_attempt.notify_one();
-                                return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                    std_io::ErrorKind::ConnectionRefused,
-                                    "connection refused",
-                                )));
-                            }
-                            Ok(())
-                        }
-                    },
-                    Duration::from_millis(100),
-                )
-                .await
-        });
-
-        first_attempt.notified().await;
-        tokio::task::yield_now().await;
-        remote_disk.health.reset_for_store_init_retry(&remote_disk.endpoint);
-        let channel = TonicEndpoint::from_shared(remote_disk.addr.clone())
-            .expect("remote disk address should parse")
-            .connect_lazy();
-        runtime_sources::cache_test_node_channel(remote_disk.addr.clone(), channel).await;
-        task.await
-            .expect("retry task should finish")
-            .expect("the retry should succeed after the health reset");
-
-        assert_eq!(attempts.load(Ordering::SeqCst), 2);
-        assert_eq!(started.elapsed(), Duration::from_millis(70));
-        assert_eq!(
-            remote_disk.health.waiting_count(),
-            0,
-            "health reset must not underflow the waiting counter"
-        );
-        assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Online);
-        assert!(
-            runtime_sources::test_node_channel_is_cached(&remote_disk.addr).await,
-            "a recovered channel must survive the retry backoff"
-        );
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_still_retries_within_shared_deadline() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let channel = TonicEndpoint::from_shared(remote_disk.addr.clone())
-            .expect("remote disk address should parse")
-            .connect_lazy();
-        runtime_sources::cache_test_node_channel(remote_disk.addr.clone(), channel).await;
-
-        remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    let attempt = attempts.fetch_add(1, Ordering::SeqCst);
-                    async move {
-                        if attempt == 0 {
-                            return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionReset,
-                                "connection reset",
-                            )));
-                        }
-                        Ok(())
-                    }
-                },
-                Duration::from_millis(100),
-            )
-            .await
-            .expect("a retry that fits the shared deadline should succeed");
-
-        assert_eq!(attempts.load(Ordering::SeqCst), 2);
-        assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Online);
-        assert!(runtime_sources::test_node_channel_is_cached(&remote_disk.addr).await);
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_uses_remaining_budget_for_final_attempt() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let started = time::Instant::now();
-        let channel = TonicEndpoint::from_shared(remote_disk.addr.clone())
-            .expect("remote disk address should parse")
-            .connect_lazy();
-        runtime_sources::cache_test_node_channel(remote_disk.addr.clone(), channel).await;
-
-        let err = remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    let attempt = attempts.fetch_add(1, Ordering::SeqCst);
-                    async move {
-                        if attempt == 0 {
-                            time::sleep(Duration::from_millis(20)).await;
-                            return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionRefused,
-                                "connection refused",
-                            )));
-                        }
-                        std::future::pending::<Result<()>>().await
-                    }
-                },
-                Duration::from_millis(100),
-            )
-            .await
-            .expect_err("the final retry should consume only the remaining total budget");
-
-        assert_eq!(err, DiskError::Timeout);
-        assert_eq!(attempts.load(Ordering::SeqCst), 2);
-        assert_eq!(started.elapsed(), Duration::from_millis(100));
-        assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Suspect);
-        assert!(!runtime_sources::test_node_channel_is_cached(&remote_disk.addr).await);
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_uses_final_attempt_at_exact_backoff_boundary() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let started = time::Instant::now();
-
-        let err = remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    let attempt = attempts.fetch_add(1, Ordering::SeqCst);
-                    async move {
-                        if attempt == 0 {
-                            time::sleep(Duration::from_millis(50)).await;
-                            return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionRefused,
-                                "connection refused",
-                            )));
-                        }
-                        std::future::pending::<Result<()>>().await
-                    }
-                },
-                Duration::from_millis(100),
-            )
-            .await
-            .expect_err("the exact backoff boundary should be reserved for a final attempt");
-
-        assert_eq!(err, DiskError::Timeout);
-        assert_eq!(attempts.load(Ordering::SeqCst), 2);
-        assert_eq!(started.elapsed(), Duration::from_millis(100));
-        assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Suspect);
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_uses_final_attempt_below_backoff_budget() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let started = time::Instant::now();
-
-        let err = remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    let attempt = attempts.fetch_add(1, Ordering::SeqCst);
-                    async move {
-                        if attempt == 0 {
-                            time::sleep(Duration::from_millis(80)).await;
-                            return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionRefused,
-                                "connection refused",
-                            )));
-                        }
-                        std::future::pending::<Result<()>>().await
-                    }
-                },
-                Duration::from_millis(100),
-            )
-            .await
-            .expect_err("remaining budget below backoff should be reserved for a final attempt");
-
-        assert_eq!(err, DiskError::Timeout);
-        assert_eq!(attempts.load(Ordering::SeqCst), 2);
-        assert_eq!(started.elapsed(), Duration::from_millis(100));
-        assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Suspect);
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_zero_timeout_disables_the_deadline() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let started = time::Instant::now();
-
-        remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    let attempt = attempts.fetch_add(1, Ordering::SeqCst);
-                    async move {
-                        if attempt == 0 {
-                            return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionReset,
-                                "connection reset",
-                            )));
-                        }
-                        Ok(())
-                    }
-                },
-                Duration::ZERO,
-            )
-            .await
-            .expect("zero timeout should allow a retry without a deadline");
-
-        assert_eq!(attempts.load(Ordering::SeqCst), 2);
-        assert_eq!(started.elapsed(), REMOTE_DISK_READ_RETRY_BASE_BACKOFF);
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_accepts_max_metadata_timeout() {
-        temp_env::async_with_vars([(rustfs_config::ENV_DRIVE_METADATA_TIMEOUT_SECS, Some(u64::MAX.to_string()))], async {
-            let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-
-            remote_disk
-                .execute_read_with_retry("read_version", || async { Ok::<(), Error>(()) }, get_drive_metadata_timeout())
-                .await
-                .expect("the maximum configured metadata timeout must not panic");
-
-            remote_disk.cancel_token.cancel();
-        })
-        .await;
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_zero_retries_runs_once() {
-        temp_env::async_with_vars([(rustfs_config::ENV_INTERNODE_IDEMPOTENT_READ_RETRIES, Some("0"))], async {
-            let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-            let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-            let started = time::Instant::now();
-            let channel = TonicEndpoint::from_shared(remote_disk.addr.clone())
-                .expect("remote disk address should parse")
-                .connect_lazy();
-            runtime_sources::cache_test_node_channel(remote_disk.addr.clone(), channel).await;
-
-            let err = remote_disk
-                .execute_read_with_retry(
-                    "read_version",
-                    || {
-                        attempts.fetch_add(1, Ordering::SeqCst);
-                        async {
-                            Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionReset,
-                                "connection reset",
-                            )))
-                        }
-                    },
-                    Duration::from_secs(1),
-                )
-                .await
-                .expect_err("zero retries should return the first network error");
-
-            assert!(matches!(err, DiskError::Io(ref io_err) if io_err.kind() == std_io::ErrorKind::ConnectionReset));
-            assert_eq!(attempts.load(Ordering::SeqCst), 1);
-            assert_eq!(started.elapsed(), Duration::ZERO);
-            assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Suspect);
-            assert!(!runtime_sources::test_node_channel_is_cached(&remote_disk.addr).await);
-            remote_disk.cancel_token.cancel();
-        })
-        .await;
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_attempt_timeout_marks_health_without_evicting() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let recorder = crate::test_metrics::CapturingRecorder::default();
-        let _recorder_guard = metrics::set_default_local_recorder(&recorder);
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let channel = TonicEndpoint::from_shared(remote_disk.addr.clone())
-            .expect("remote disk address should parse")
-            .connect_lazy();
-        runtime_sources::cache_test_node_channel(remote_disk.addr.clone(), channel).await;
-
-        let err = remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    attempts.fetch_add(1, Ordering::SeqCst);
-                    std::future::pending::<Result<()>>()
-                },
-                Duration::from_millis(100),
-            )
-            .await
-            .expect_err("an in-flight attempt that consumes the deadline should time out");
-
-        assert_eq!(err, DiskError::Timeout);
-        assert_eq!(attempts.load(Ordering::SeqCst), 1);
-        assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Suspect);
-        assert!(runtime_sources::test_node_channel_is_cached(&remote_disk.addr).await);
-        assert_eq!(
-            recorder.counter_value(
-                "rustfs_drive_op_timeout_total",
-                &[
-                    ("endpoint", remote_disk.endpoint.to_string().as_str()),
-                    ("op", "read_version")
-                ]
-            ),
-            1
-        );
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_does_not_retry_business_errors() {
-        let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-
-        let err = remote_disk
-            .execute_read_with_retry(
-                "read_version",
-                || {
-                    attempts.fetch_add(1, Ordering::SeqCst);
-                    async { Err::<(), Error>(DiskError::FileNotFound) }
-                },
-                Duration::from_secs(1),
-            )
-            .await
-            .expect_err("business errors should be returned directly");
-
-        assert_eq!(err, DiskError::FileNotFound);
-        assert_eq!(attempts.load(Ordering::SeqCst), 1);
-        remote_disk.cancel_token.cancel();
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_honors_configured_retry_count() {
-        temp_env::async_with_vars([(rustfs_config::ENV_INTERNODE_IDEMPOTENT_READ_RETRIES, Some("2"))], async {
-            let remote_disk = new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await;
-            let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-            let started = time::Instant::now();
-            let channel = TonicEndpoint::from_shared(remote_disk.addr.clone())
-                .expect("remote disk address should parse")
-                .connect_lazy();
-            runtime_sources::cache_test_node_channel(remote_disk.addr.clone(), channel).await;
-
-            let err = remote_disk
-                .execute_read_with_retry(
-                    "read_version",
-                    || {
-                        attempts.fetch_add(1, Ordering::SeqCst);
-                        async {
-                            Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                std_io::ErrorKind::ConnectionReset,
-                                "connection reset",
-                            )))
-                        }
-                    },
-                    Duration::from_secs(1),
-                )
-                .await
-                .expect_err("exhausted retries should return the last network error");
-
-            assert!(matches!(err, DiskError::Io(ref io_err) if io_err.kind() == std_io::ErrorKind::ConnectionReset));
-            assert_eq!(attempts.load(Ordering::SeqCst), 3);
-            assert_eq!(started.elapsed(), Duration::from_millis(150));
-            assert_eq!(remote_disk.runtime_state(), RuntimeDriveHealthState::Suspect);
-            assert!(!runtime_sources::test_node_channel_is_cached(&remote_disk.addr).await);
-            remote_disk.cancel_token.cancel();
-        })
-        .await;
-    }
-
-    #[tokio::test(start_paused = true)]
-    #[serial(remote_disk_read_retry)]
-    async fn execute_read_with_retry_stops_when_disk_turns_offline_during_backoff() {
-        let remote_disk = Arc::new(new_remote_disk_with_transport(Arc::new(RecordingInternodeDataTransport::default())).await);
-        let attempts = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let first_attempt = Arc::new(tokio::sync::Notify::new());
-        let task_disk = Arc::clone(&remote_disk);
-        let task_attempts = Arc::clone(&attempts);
-        let task_first_attempt = Arc::clone(&first_attempt);
-
-        let task = tokio::spawn(async move {
-            task_disk
-                .execute_read_with_retry(
-                    "read_version",
-                    move || {
-                        let attempt = task_attempts.fetch_add(1, Ordering::SeqCst);
-                        let first_attempt = Arc::clone(&task_first_attempt);
-                        async move {
-                            if attempt == 0 {
-                                first_attempt.notify_one();
-                                return Err::<(), Error>(DiskError::Io(std_io::Error::new(
-                                    std_io::ErrorKind::ConnectionReset,
-                                    "connection reset",
-                                )));
-                            }
-                            Ok(())
-                        }
-                    },
-                    Duration::from_secs(1),
-                )
-                .await
-        });
-
-        first_attempt.notified().await;
-        tokio::task::yield_now().await;
-        remote_disk
-            .health
-            .force_runtime_state_for_test(RuntimeDriveHealthState::Offline);
-        time::advance(REMOTE_DISK_READ_RETRY_BASE_BACKOFF).await;
-        let err = task
-            .await
-            .expect("retry task should finish")
-            .expect_err("an offline disk must stop before the next attempt");
-
-        assert_eq!(err, DiskError::FaultyDisk);
-        assert_eq!(attempts.load(Ordering::SeqCst), 1);
-        remote_disk.cancel_token.cancel();
-    }
-
    #[tokio::test]
    async fn test_execute_with_timeout_evicts_cached_connection() {
        let addr = "http://127.0.0.1:59991".to_string();
@@ -6137,40 +5603,6 @@ mod tests {
        accept_task.abort();
    }

-    #[tokio::test]
-    async fn read_version_uses_the_metadata_timeout_on_a_stalled_peer() {
-        runtime_sources::ensure_test_rpc_secret();
-        let Some((base_addr, accept_task)) = spawn_stalled_grpc_peer().await else {
-            return;
-        };
-        let remote_disk = remote_disk_for_addr(&base_addr).await;
-
-        temp_env::async_with_vars(
-            [
-                (rustfs_config::ENV_DRIVE_METADATA_TIMEOUT_SECS, Some("1")),
-                (rustfs_config::ENV_DRIVE_MAX_TIMEOUT_DURATION, Some("10")),
-            ],
-            async {
-                let started = time::Instant::now();
-                let err = tokio::time::timeout(
-                    Duration::from_secs(5),
-                    remote_disk.read_version("bucket", "bucket", "object", "", &ReadOptions::default()),
-                )
-                .await
-                .expect("read_version must use the shorter metadata deadline")
-                .expect_err("a stalled peer must fail read_version");
-
-                assert!(matches!(err, DiskError::Timeout), "expected the metadata deadline to fire, got {err:?}");
-                assert!(started.elapsed() >= Duration::from_millis(900));
-                assert!(started.elapsed() < Duration::from_secs(2));
-            },
-        )
-        .await;
-
-        remote_disk.cancel_token.cancel();
-        accept_task.abort();
-    }
-
    #[tokio::test]
    async fn delete_volume_bounds_the_wait_on_a_stalled_peer() {
        runtime_sources::ensure_test_rpc_secret();
@@ -2266,19 +2266,15 @@ fn decommission_delete_marker_opts(
    version: &rustfs_filemeta::FileInfo,
    version_id: Option<String>,
    src_pool_idx: usize,
-    expected_bucket_incarnation_id: Option<uuid::Uuid>,
 ) -> ObjectOptions {
-    let version_suspended = version.version_id.is_none() && version_id.is_none();
    ObjectOptions {
-        versioned: !version_suspended,
-        version_suspended,
-        version_id: version_id.or_else(|| version_suspended.then(|| uuid::Uuid::nil().to_string())),
+        versioned: true,
+        version_id,
        mod_time: version.mod_time,
        src_pool_idx,
        data_movement: true,
        delete_marker: true,
        skip_decommissioned: true,
-        expected_bucket_incarnation_id,
        delete_replication: version
            .replication_state_internal
            .as_ref()
@@ -2303,7 +2299,6 @@ fn decommission_remote_tiered_opts(
    version: &rustfs_filemeta::FileInfo,
    version_id: Option<String>,
    src_pool_idx: usize,
-    expected_bucket_incarnation_id: Option<uuid::Uuid>,
 ) -> ObjectOptions {
    ObjectOptions {
        versioned: version_id.is_some(),
@@ -2312,9 +2307,6 @@ fn decommission_remote_tiered_opts(
        user_defined: version.metadata.clone(),
        src_pool_idx,
        data_movement: true,
-        include_part_checksums: true,
-        http_preconditions: Some(crate::data_movement::data_movement_target_precondition()),
-        expected_bucket_incarnation_id,
        ..Default::default()
    }
 }
@@ -2813,7 +2805,6 @@ impl ECStore {
        lifecycle_config: Option<BucketLifecycleConfiguration>,
        object_lock_config: Option<ObjectLockConfiguration>,
        replication_config: Option<(ReplicationConfiguration, OffsetDateTime)>,
-        expected_bucket_incarnation_id: Option<uuid::Uuid>,
    ) -> Result<()> {
        debug!(
            event = EVENT_DECOMMISSION_ENTRY,
@@ -2843,11 +2834,6 @@ impl ECStore {
        }
        decommission_cancel_signal_result(rx.is_cancelled())?;

-        let bucket_incarnation_fence = match expected_bucket_incarnation_id {
-            Some(expected) => Some(self.acquire_bucket_incarnation_fence(&bucket, expected).await?),
-            None => None,
-        };
-
        let mut fivs = load_decommission_entry_exact_versions(&set, &entry, &bucket, "file_info_versions").await?;

        fivs.versions
@@ -2908,7 +2894,7 @@ impl ECStore {
                    .delete_object(
                        bucket.as_str(),
                        &version.name,
-                        decommission_delete_marker_opts(version, version_id.clone(), idx, expected_bucket_incarnation_id),
+                        decommission_delete_marker_opts(version, version_id.clone(), idx),
                    )
                    .await
                {
@@ -2998,7 +2984,7 @@ impl ECStore {
                            bucket.as_str(),
                            &version.name,
                            version,
-                            &decommission_remote_tiered_opts(version, version_id.clone(), idx, expected_bucket_incarnation_id),
+                            &decommission_remote_tiered_opts(version, version_id.clone(), idx),
                        )
                        .await
                    {
@@ -3070,11 +3056,7 @@ impl ECStore {
                )
                .await?;

-                if let Err(err) = self
-                    .clone()
-                    .decommission_object(idx, bucket, rd, expected_bucket_incarnation_id)
-                    .await
-                {
+                if let Err(err) = self.clone().decommission_object(idx, bucket, rd).await {
                    if is_decommission_copy_cleanup_safe_error(&err) {
                        ignore = true;
                        cleanup_ignored = true;
@@ -3151,9 +3133,6 @@ impl ECStore {
        }

        if should_cleanup_decommission_source_entry(decommissioned, fivs.versions.len(), expired) {
-            if bucket_incarnation_fence.as_ref().is_some_and(|guard| guard.is_lock_lost()) {
-                return Err(Error::other("decommission bucket incarnation fence was lost before source cleanup"));
-            }
            decommission_cancel_signal_result(rx.is_cancelled())?;

            self.save_decommission_entry_progress_stage(
@@ -3178,12 +3157,6 @@ impl ECStore {
                entry.name.as_str(),
                &fivs,
                &cleanup_preflight_allowed_missing,
-                data_movement::SourceCleanupBucketFence {
-                    expected_incarnation_id: expected_bucket_incarnation_id,
-                    lifecycle_guard: bucket_incarnation_fence
-                        .as_ref()
-                        .and_then(|guard| guard.namespace_lock_guard()),
-                },
                "decommission",
            )
            .await
@@ -3295,11 +3268,6 @@ impl ECStore {
        let mut lifecycle_config = None;
        let mut object_lock_config = None;
        let mut replication_config = None;
-        let expected_bucket_incarnation_id = if bi.name == RUSTFS_META_BUCKET {
-            None
-        } else {
-            Some(self.bucket_incarnation_id_from_disk(&bi.name).await?)
-        };

        if bi.name != RUSTFS_META_BUCKET {
            let _ = resolve_decommission_optional_bucket_config_result(
@@ -3353,7 +3321,6 @@ impl ECStore {
                    let lifecycle_config = lifecycle_config.clone();
                    let object_lock_config = object_lock_config.clone();
                    let replication_config = replication_config.clone();
-                    let expected_bucket_incarnation_id = expected_bucket_incarnation_id;
                    let entry_error = entry_error.clone();
                    let callback_rx = callback_rx.clone();

@@ -3416,7 +3383,6 @@ impl ECStore {
                                lifecycle_config,
                                object_lock_config,
                                replication_config,
-                                expected_bucket_incarnation_id,
                            )
                            .await
                        {
@@ -4202,24 +4168,10 @@ impl ECStore {
    }

    #[tracing::instrument(skip(self, rd))]
-    async fn decommission_object(
-        self: Arc<Self>,
-        pool_idx: usize,
-        bucket: String,
-        rd: GetObjectReader,
-        expected_bucket_incarnation_id: Option<uuid::Uuid>,
-    ) -> Result<()> {
+    async fn decommission_object(self: Arc<Self>, pool_idx: usize, bucket: String, rd: GetObjectReader) -> Result<()> {
        warn!("decommission_object: start {} {}", &bucket, &rd.object_info.name);
        let object_name = rd.object_info.name.clone();
-        let result = data_movement::migrate_object(
-            self,
-            pool_idx,
-            bucket.clone(),
-            rd,
-            expected_bucket_incarnation_id,
-            "decommission_object",
-        )
-        .await;
+        let result = data_movement::migrate_object(self, pool_idx, bucket.clone(), rd, "decommission_object").await;
        if result.is_ok() {
            warn!("decommission_object: migrated {} {}", &bucket, &object_name);
        }
@@ -4395,8 +4347,7 @@ mod tests {
            ..Default::default()
        };

-        let incarnation = uuid::Uuid::new_v4();
-        let opts = decommission_delete_marker_opts(&version, Some("version-id".to_string()), 7, Some(incarnation));
+        let opts = decommission_delete_marker_opts(&version, Some("version-id".to_string()), 7);
        let replication = opts.delete_replication.expect("replication state should be preserved");

        assert!(opts.versioned);
@@ -4406,25 +4357,11 @@ mod tests {
        assert_eq!(opts.src_pool_idx, 7);
        assert_eq!(opts.version_id.as_deref(), Some("version-id"));
        assert_eq!(opts.mod_time, Some(mod_time));
-        assert_eq!(opts.expected_bucket_incarnation_id, Some(incarnation));
        assert_eq!(replication.replica_status, ReplicationStatusType::Replica);
        assert!(replication.delete_marker);
        assert_eq!(replication.replicate_decision_str, "existing");
    }

-    #[test]
-    fn decommission_delete_marker_opts_preserves_suspended_null_version() {
-        let version = rustfs_filemeta::FileInfo {
-            deleted: true,
-            ..Default::default()
-        };
-        let opts = decommission_delete_marker_opts(&version, None, 7, None);
-
-        assert!(!opts.versioned);
-        assert!(opts.version_suspended);
-        assert_eq!(opts.version_id.as_deref(), Some(uuid::Uuid::nil().to_string().as_str()));
-    }
-
    #[test]
    fn test_decommission_object_migration_read_opts_are_raw_data_movement() {
        let opts = decommission_object_migration_read_opts(Some("vid-1".to_string()));
@@ -4446,8 +4383,7 @@ mod tests {
            ..Default::default()
        };

-        let incarnation = uuid::Uuid::new_v4();
-        let opts = decommission_remote_tiered_opts(&version, Some("version-id".to_string()), 9, Some(incarnation));
+        let opts = decommission_remote_tiered_opts(&version, Some("version-id".to_string()), 9);

        assert!(opts.versioned);
        assert!(opts.data_movement);
@@ -4455,9 +4391,6 @@ mod tests {
        assert_eq!(opts.version_id.as_deref(), Some("version-id"));
        assert_eq!(opts.mod_time, Some(mod_time));
        assert_eq!(opts.user_defined.get("x-amz-meta-key").map(String::as_str), Some("value"));
-        assert!(opts.include_part_checksums);
-        assert!(opts.http_preconditions.is_some());
-        assert_eq!(opts.expected_bucket_incarnation_id, Some(incarnation));
    }

    #[test]
@@ -137,7 +137,6 @@ pub(crate) const GET_METADATA_CACHE_REASON_NO_LOCK: &str = "no_lock";
 pub(crate) const GET_METADATA_CACHE_REASON_NOT_FOUND_OR_EXPIRED: &str = "not_found_or_expired";
 pub(crate) const GET_METADATA_CACHE_REASON_NOT_READ_DATA: &str = "not_read_data";
 pub(crate) const GET_METADATA_CACHE_REASON_PART_NUMBER: &str = "part_number";
-pub(crate) const GET_METADATA_CACHE_REASON_PART_CHECKSUMS: &str = "part_checksums";
 pub(crate) const GET_METADATA_CACHE_REASON_RAW_DATA_MOVEMENT_READ: &str = "raw_data_movement_read";
 pub(crate) const GET_METADATA_CACHE_REASON_STALE_PUBLICATION: &str = "stale_publication";
 pub(crate) const GET_METADATA_CACHE_REASON_USABLE: &str = "usable";
@@ -481,7 +480,6 @@ mod tests {
        assert_eq!(GET_METADATA_CACHE_REASON_NO_LOCK, "no_lock");
        assert_eq!(GET_METADATA_CACHE_REASON_NOT_FOUND_OR_EXPIRED, "not_found_or_expired");
        assert_eq!(GET_METADATA_CACHE_REASON_NOT_READ_DATA, "not_read_data");
-        assert_eq!(GET_METADATA_CACHE_REASON_PART_CHECKSUMS, "part_checksums");
        assert_eq!(GET_METADATA_CACHE_REASON_PART_NUMBER, "part_number");
        assert_eq!(GET_METADATA_CACHE_REASON_RAW_DATA_MOVEMENT_READ, "raw_data_movement_read");
        assert_eq!(GET_METADATA_CACHE_REASON_STALE_PUBLICATION, "stale_publication");
@@ -2022,21 +2022,6 @@ impl DiskAPI for LocalDiskWrapper {
        .await
    }

-    async fn read_file_stream_chunks(
-        &self,
-        volume: &str,
-        path: &str,
-        offset: usize,
-        length: usize,
-    ) -> Result<Option<rustfs_rio::ChunkReaderBox>> {
-        self.track_disk_health_with_op(
-            "read_file_stream_chunks",
-            || async { self.disk.read_file_stream_chunks(volume, path, offset, length).await },
-            get_max_timeout_duration(),
-        )
-        .await
-    }
-
    async fn read_file_mmap_copy(&self, volume: &str, path: &str, offset: usize, length: usize) -> Result<bytes::Bytes> {
        self.track_disk_health_with_op(
            "read_file_mmap_copy",
@@ -113,9 +113,6 @@ pub enum DiskError {
    #[error("bit-rot hash algorithm is invalid")]
    BitrotHashAlgoInvalid,

-    /// Never constructed locally by RustFS (only reachable through wire
-    /// decoding, and no current node sends it). The wire code is kept for
-    /// cross-version compatibility — do not renumber or remove (backlog#1831).
    #[error("Rename across devices not allowed, please fix your backend configuration")]
    CrossDeviceLink,

@@ -146,9 +143,6 @@ pub enum DiskError {
    #[error("io error {0}")]
    Io(#[source] io::Error),

-    /// Never constructed locally by RustFS (only reachable through wire
-    /// decoding, and no current node sends it). The wire code is kept for
-    /// cross-version compatibility — do not renumber or remove (backlog#1831).
    #[error("source stalled")]
    SourceStalled,

@@ -648,6 +642,19 @@ impl Hash for DiskError {
 // is currently commented out to avoid complexity. These can be re-enabled
 // when needed for specific disk quorum checking and error aggregation logic.

+/// Bitrot errors
+#[derive(Debug, thiserror::Error)]
+pub enum BitrotErrorType {
+    #[error("bitrot checksum verification failed")]
+    BitrotChecksumMismatch { expected: String, got: String },
+}
+
+impl From<BitrotErrorType> for DiskError {
+    fn from(e: BitrotErrorType) -> Self {
+        DiskError::other(e)
+    }
+}
+
 /// Context wrapper for file access errors
 #[derive(Debug, thiserror::Error)]
 pub struct FileAccessDeniedWithContext {
@@ -862,6 +869,19 @@ mod tests {
        let _disk_error: DiskError = json_error.into();
    }

+    #[test]
+    fn test_bitrot_error_type() {
+        let bitrot_error = BitrotErrorType::BitrotChecksumMismatch {
+            expected: "abc123".to_string(),
+            got: "def456".to_string(),
+        };
+
+        assert!(bitrot_error.to_string().contains("bitrot checksum verification failed"));
+
+        let disk_error: DiskError = bitrot_error.into();
+        assert!(matches!(disk_error, DiskError::Io(_)));
+    }
+
    #[test]
    fn test_file_access_denied_with_context() {
        let path = PathBuf::from("/test/path");
@@ -9174,7 +9174,7 @@ impl DiskAPI for LocalDisk {

            if let Some(src_file_path_parent) = src_file_path.parent() {
                if src_volume != super::RUSTFS_META_MULTIPART_BUCKET {
-                    let _ = std::fs::remove_dir(src_file_path_parent);
+                    let _ = remove_std(src_file_path_parent);
                } else {
                    let _ = self
                        .delete_file(&dst_volume_dir, &src_file_path_parent.to_path_buf(), true, false)
@@ -9499,7 +9499,7 @@ impl DiskAPI for LocalDisk {
            if let Some(ref cleanup) = cleanup_path {
                let _ = self.delete_file(&dst_volume_dir, cleanup, true, false).await;
            } else if let Some(parent) = src_file_path.parent() {
-                let _ = std::fs::remove_dir(parent);
+                let _ = remove_std(parent);
            }

            // Heal reuses a version's `data_dir` and lands the rebuilt shard on
@@ -9875,7 +9875,6 @@ impl DiskAPI for LocalDisk {
            FileInfoOpts {
                data: read_data,
                include_free_versions: opts.incl_free_versions,
-                include_part_checksums: false,
            },
        )?;

@@ -12440,10 +12439,6 @@ mod test {
            .join(RUSTFS_META_TMP_BUCKET)
            .join(tmp_object)
            .join(new_data_dir.to_string());
-        let tmp_parent = tmp_data_dir
-            .parent()
-            .expect("tmp data dir should have a parent")
-            .to_path_buf();
        fs::create_dir_all(&tmp_data_dir)
            .await
            .expect("new tmp data dir should be created");
@@ -12455,10 +12450,6 @@ mod test {
        disk.rename_data(RUSTFS_META_TMP_BUCKET, tmp_object, new_fi, bucket, object)
            .await
            .expect("rename_data should commit");
-        assert!(
-            !tmp_parent.exists(),
-            "successful non-inline commit should remove the empty staging parent"
-        );

        // The tmp xl.meta write point uses SyncMode::FileOnly: its parent dir
        // ({tmp}/{tmp_object}) must not be fsynced.
@@ -12663,9 +12654,6 @@ mod test {
        let tmp_object = "tmp-new-inline";
        ensure_test_volume(&disk, bucket).await;
        ensure_test_volume(&disk, RUSTFS_META_TMP_BUCKET).await;
-        let tmp_parent = disk
-            .get_object_path(RUSTFS_META_TMP_BUCKET, tmp_object)
-            .expect("tmp parent should resolve");

        let _mode = durability_mode_override::set(DurabilityMode::Strict);
        let version_id = Uuid::parse_str("99999999-9999-9999-9999-999999999999").expect("version id should parse");
@@ -12674,7 +12662,6 @@ mod test {
        disk.rename_data(RUSTFS_META_TMP_BUCKET, tmp_object, new_fi, bucket, object)
            .await
            .expect("inline rename_data should commit the new object");
-        assert!(!tmp_parent.exists(), "successful inline commit should remove the empty staging parent");

        let bucket_dir = disk.get_bucket_path(bucket).expect("bucket path should resolve");
        let prefix_dir = disk.get_object_path(bucket, "prefix").expect("prefix path should resolve");
@@ -12698,34 +12685,6 @@ mod test {
        );
    }

-    #[tokio::test]
-    async fn rename_data_inline_preserves_non_empty_staging_parent() {
-        use tempfile::tempdir;
-
-        let dir = tempdir().expect("temp dir should be created");
-        let endpoint = Endpoint::try_from(dir.path().to_str().expect("temp dir should be utf8")).expect("endpoint should parse");
-        let disk = LocalDisk::new(&endpoint, false).await.expect("local disk should be created");
-        let bucket = "inline-staging-sentinel-bucket";
-        let object = "inline-object";
-        let tmp_object = "inline-stage-with-sentinel";
-        ensure_test_volume(&disk, bucket).await;
-        ensure_test_volume(&disk, RUSTFS_META_TMP_BUCKET).await;
-
-        let tmp_parent = disk
-            .get_object_path(RUSTFS_META_TMP_BUCKET, tmp_object)
-            .expect("tmp parent should resolve");
-        fs::create_dir_all(&tmp_parent).await.expect("tmp parent should be created");
-        let sentinel = tmp_parent.join("sentinel");
-        fs::write(&sentinel, b"keep").await.expect("sentinel should be written");
-
-        let fi = test_file_info(object, Uuid::new_v4(), None, Some(Bytes::from_static(b"inline-payload")));
-        disk.rename_data(RUSTFS_META_TMP_BUCKET, tmp_object, fi, bucket, object)
-            .await
-            .expect("non-empty staging cleanup must not negate the committed object");
-
-        assert_eq!(fs::read(&sentinel).await.expect("sentinel should remain"), b"keep");
-    }
-
    #[cfg(unix)]
    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
    #[allow(clippy::await_holding_lock)]
@@ -12900,10 +12859,7 @@ mod test {
            .expect("non-inline rename_data should commit");

        assert!(!replacement_dir.exists(), "the destination object directory must not be replaced");
-        assert!(
-            !staging_parent.exists(),
-            "successful commit should remove the empty staging parent after releasing its guard"
-        );
+        assert!(staging_parent.exists(), "the guarded staging parent must retain its identity");
        assert!(
            !replacement_staging_parent.exists(),
            "the staging parent must not be replaced between data and metadata publication"
@@ -65,7 +65,6 @@ use error::{Error, Result};
 use local::LocalDisk;
 use rustfs_filemeta::{FileInfo, ObjectPartInfo, RawFileInfo};
 use rustfs_madmin::info_commands::DiskMetrics;
-use rustfs_rio::ChunkReaderBox;
 use serde::{Deserialize, Serialize};
 use std::{fmt::Debug, path::PathBuf, sync::Arc, time::Duration};
 use time::OffsetDateTime;
@@ -428,19 +427,6 @@ impl DiskAPI for Disk {
        }
    }

-    async fn read_file_stream_chunks(
-        &self,
-        volume: &str,
-        path: &str,
-        offset: usize,
-        length: usize,
-    ) -> Result<Option<ChunkReaderBox>> {
-        match self {
-            Disk::Local(_) => Ok(None),
-            Disk::Remote(remote_disk) => remote_disk.read_file_stream_chunks(volume, path, offset, length).await,
-        }
-    }
-
    #[tracing::instrument(level = "trace", skip_all)]
    async fn read_file_mmap_copy(&self, volume: &str, path: &str, offset: usize, length: usize) -> Result<Bytes> {
        match self {
@@ -879,18 +865,6 @@ pub trait DiskAPI: Debug + Send + Sync + 'static {
    async fn read_file(&self, volume: &str, path: &str) -> Result<FileReader>;
    async fn read_file_stream(&self, volume: &str, path: &str, offset: usize, length: usize) -> Result<FileReader>;

-    /// Returns an owned-chunk stream when the backing transport can preserve
-    /// receive-buffer ownership. `None` retains the ordinary reader path.
-    async fn read_file_stream_chunks(
-        &self,
-        _volume: &str,
-        _path: &str,
-        _offset: usize,
-        _length: usize,
-    ) -> Result<Option<ChunkReaderBox>> {
-        Ok(None)
-    }
-
    /// File read using mmap-then-copy on Unix or an efficient read on non-Unix.
    async fn read_file_mmap_copy(&self, volume: &str, path: &str, offset: usize, length: usize) -> Result<Bytes>;

@@ -76,13 +76,6 @@ impl ShardBufferPool {
        self.buffers[index] = Some(buf);
    }

-    #[cfg(test)]
-    pub(crate) fn stored_allocation(&self, index: usize) -> Option<(*const u8, usize)> {
-        self.buffers
-            .get(index)
-            .and_then(|buf| buf.as_ref().map(|buf| (buf.as_ptr(), buf.capacity())))
-    }
-
    #[cfg(test)]
    fn stored_capacity(&self, index: usize) -> Option<usize> {
        self.buffers.get(index).and_then(|buf| buf.as_ref().map(Vec::capacity))
@@ -14,10 +14,7 @@

 use pin_project_lite::pin_project;
 use rustfs_utils::HashAlgorithm;
-use std::future::poll_fn;
 use std::io::IoSlice;
-use std::pin::Pin;
-use std::task::{Context, Poll};
 use std::time::Duration;
 use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
 use tracing::error;
@@ -26,18 +23,6 @@ const LOG_COMPONENT_ECSTORE: &str = "ecstore";
 const LOG_SUBSYSTEM_ERASURE: &str = "erasure";
 const EVENT_BITROT_SHORT_SHARD_READ: &str = "bitrot_short_shard_read";
 const EVENT_BITROT_HASH_MISMATCH: &str = "bitrot_hash_mismatch";
-const MAX_RETAINED_CHUNKS_PER_BLOCK: usize = 64;
-const MAX_CHUNK_POLLS_PER_YIELD: usize = MAX_RETAINED_CHUNKS_PER_BLOCK + 1;
-
-/// Result of polling an optional owned-chunk handoff.
-pub enum ShardChunkRead {
-    /// The source does not support owned-chunk handoff and remains untouched.
-    Unsupported,
-    /// The source reached EOF.
-    Eof,
-    /// A non-empty chunk containing at most the requested number of bytes.
-    Chunk(bytes::Bytes),
-}

 /// A shard source that may already hold its bytes in memory.
 ///
@@ -57,12 +42,6 @@ pub trait ShardSource: AsyncRead + Send + Sync + Unpin {
    fn try_take_block(&mut self, _n: usize) -> Option<bytes::Bytes> {
        None
    }
-
-    /// Polls one owned chunk when the source supports chunk handoff.
-    /// `Unsupported` must leave the source untouched.
-    fn poll_read_chunk(self: Pin<&mut Self>, _cx: &mut Context<'_>, _max: usize) -> Poll<std::io::Result<ShardChunkRead>> {
-        Poll::Ready(Ok(ShardChunkRead::Unsupported))
-    }
 }

 /// Borrowed and owned byte slices are ordinary streaming sources: they carry no
@@ -96,9 +75,6 @@ pin_project! {
        // contiguous on-disk `[hash][data]` block so both are pulled in a single
        // pass; grown lazily and never shrunk.
        buf: Vec<u8>,
-        // Reused owned chunk vector for the remote HTTP fast path. Keeping the
-        // allocation with the reader avoids allocating once per bitrot block.
-        chunks: Vec<bytes::Bytes>,
        skip_verify: bool,
        last_verify_duration: Duration,
    }
@@ -115,7 +91,6 @@ where
            hash_algo: algo,
            shard_size,
            buf: Vec::new(),
-            chunks: Vec::new(),
            skip_verify,
            last_verify_duration: Duration::ZERO,
        }
@@ -125,11 +100,6 @@ where
        self.last_verify_duration
    }

-    #[cfg(test)]
-    pub(crate) fn inner_ref(&self) -> &R {
-        &self.inner
-    }
-
    /// Read a single (hash+data) block, verify hash, and copy `out.len()` bytes
    /// into `out`. Returns an error if the shard is short, the hash mismatches,
    /// or `out` is larger than one shard. On error `out`'s contents are
@@ -290,6 +260,11 @@ where

        let need = hash_size + want;

+        // In-memory fast path: the block is already resident, so slice it instead
+        // of copying it into the scratch buffer first (rustfs/backlog#1159). One
+        // copy (`extend_from_slice`) instead of two. A source that cannot serve
+        // `need` bytes returns `None` and falls through to the scratch path,
+        // keeping the short-read contract.
        if let Some(block) = self.inner.try_take_block(need) {
            let (data, verify) = split_and_verify(&self.hash_algo, self.skip_verify, &block)?;
            out.extend_from_slice(data);
@@ -297,126 +272,6 @@ where
            return Ok(want);
        }

-        self.chunks.clear();
-        let handed_off = {
-            let inner = &mut self.inner;
-            let chunks = &mut self.chunks;
-            let tail_buf = &mut self.buf;
-            let mut received = 0usize;
-            poll_fn(|cx| {
-                for _ in 0..MAX_CHUNK_POLLS_PER_YIELD {
-                    let next = match Pin::new(&mut *inner).poll_read_chunk(cx, need - received) {
-                        Poll::Ready(Ok(next)) => next,
-                        Poll::Ready(Err(err)) => return Poll::Ready(Err(err)),
-                        Poll::Pending => return Poll::Pending,
-                    };
-                    let chunk = match next {
-                        ShardChunkRead::Unsupported if received == 0 => return Poll::Ready(Ok(false)),
-                        ShardChunkRead::Unsupported => {
-                            return Poll::Ready(Err(std::io::Error::new(
-                                std::io::ErrorKind::InvalidData,
-                                "chunk handoff became unavailable after transferring data",
-                            )));
-                        }
-                        ShardChunkRead::Eof => {
-                            return Poll::Ready(Err(short_shard_read(received.saturating_sub(hash_size), want)));
-                        }
-                        ShardChunkRead::Chunk(chunk) => chunk,
-                    };
-
-                    if received == 0 {
-                        tail_buf.clear();
-                    }
-                    if chunk.is_empty() {
-                        return Poll::Ready(Err(std::io::Error::new(
-                            std::io::ErrorKind::InvalidData,
-                            "chunk handoff returned an empty chunk",
-                        )));
-                    }
-                    let remaining = need - received;
-                    if chunk.len() > remaining {
-                        return Poll::Ready(Err(std::io::Error::new(
-                            std::io::ErrorKind::InvalidData,
-                            "chunk handoff exceeded its requested boundary",
-                        )));
-                    }
-                    received += chunk.len();
-
-                    if chunks.len() == MAX_RETAINED_CHUNKS_PER_BLOCK {
-                        if tail_buf.is_empty() {
-                            tail_buf.reserve_exact(need - (received - chunk.len()));
-                        }
-                        tail_buf.extend_from_slice(&chunk);
-                    } else {
-                        chunks.push(chunk);
-                    }
-
-                    if received == need {
-                        return Poll::Ready(Ok(true));
-                    }
-                }
-                cx.waker().wake_by_ref();
-                Poll::Pending
-            })
-            .await?
-        };
-        if handed_off {
-            if self.chunks.len() == 1 && self.buf.is_empty() {
-                let block = &self.chunks[0];
-                let (data, verify) = split_and_verify(&self.hash_algo, self.skip_verify, block)?;
-                out.extend_from_slice(data);
-                self.last_verify_duration = verify;
-                return Ok(want);
-            }
-
-            let block_chunks = || {
-                self.chunks
-                    .iter()
-                    .map(|chunk| chunk.as_ref())
-                    .chain((!self.buf.is_empty()).then_some(self.buf.as_slice()))
-            };
-            if !self.skip_verify {
-                let verify_start = std::time::Instant::now();
-                let actual_hash = self
-                    .hash_algo
-                    .hash_encode_slices(block_chunks().scan(hash_size, |skip, chunk| {
-                        let start = (*skip).min(chunk.len());
-                        *skip -= start;
-                        Some(&chunk[start..])
-                    }));
-                let verify = verify_start.elapsed();
-                let mut hash_offset = 0;
-                let mut remaining = hash_size;
-                for chunk in block_chunks() {
-                    let take = remaining.min(chunk.len());
-                    if actual_hash.as_ref()[hash_offset..hash_offset + take] != chunk[..take] {
-                        error!(
-                            event = EVENT_BITROT_HASH_MISMATCH,
-                            component = LOG_COMPONENT_ECSTORE,
-                            subsystem = LOG_SUBSYSTEM_ERASURE,
-                            state = "failed",
-                            data_len = want,
-                            "bitrot hash mismatch"
-                        );
-                        return Err(std::io::Error::new(std::io::ErrorKind::InvalidData, "bitrot hash mismatch"));
-                    }
-                    hash_offset += take;
-                    remaining -= take;
-                    if remaining == 0 {
-                        break;
-                    }
-                }
-                self.last_verify_duration = verify;
-            }
-            let mut skip = hash_size;
-            for chunk in block_chunks() {
-                let start = skip.min(chunk.len());
-                skip -= start;
-                out.extend_from_slice(&chunk[start..]);
-            }
-            return Ok(want);
-        }
-
        // Streaming path: same single pass and same verification as `read`; only
        // the sink differs (`extend_from_slice` into `out` instead of
        // `copy_from_slice` into a pre-zeroed buffer).
@@ -822,167 +677,18 @@ impl BitrotWriterWrapper {

 #[cfg(test)]
 mod tests {
+    use super::ShardSource;
    use super::{
        BitrotReader, BitrotWriter, BitrotWriterWrapper, CustomWriter, bitrot_shard_file_size, bitrot_verify, write_all_vectored,
    };
-    use super::{MAX_RETAINED_CHUNKS_PER_BLOCK, ShardChunkRead, ShardSource};
-    use bytes::Bytes;
    use rustfs_utils::HashAlgorithm;
-    use std::collections::VecDeque;
-    use std::io::{self, Cursor, IoSlice};
-    use std::pin::Pin;
+    use std::io::{Cursor, IoSlice};
    use std::sync::{
        Arc,
        atomic::{AtomicUsize, Ordering},
    };
    use std::task::{Context, Poll};
-    use std::time::Duration;
-    use tokio::io::{AsyncRead, AsyncWrite, AsyncWriteExt, ReadBuf};
-
-    struct FragmentedSource {
-        chunks: VecDeque<Bytes>,
-    }
-
-    impl FragmentedSource {
-        fn new(bytes: Vec<u8>, fragment_sizes: &[usize]) -> Self {
-            let mut chunks = VecDeque::new();
-            let mut offset = 0;
-            for &size in fragment_sizes {
-                let end = (offset + size).min(bytes.len());
-                if offset < end {
-                    chunks.push_back(Bytes::copy_from_slice(&bytes[offset..end]));
-                }
-                offset = end;
-            }
-            if offset < bytes.len() {
-                chunks.push_back(Bytes::copy_from_slice(&bytes[offset..]));
-            }
-            Self { chunks }
-        }
-    }
-
-    impl AsyncRead for FragmentedSource {
-        fn poll_read(self: Pin<&mut Self>, _cx: &mut Context<'_>, _buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
-            Poll::Ready(Err(io::Error::other("fragmented source must use chunk handoff")))
-        }
-    }
-
-    impl ShardSource for FragmentedSource {
-        fn poll_read_chunk(mut self: Pin<&mut Self>, _cx: &mut Context<'_>, max: usize) -> Poll<io::Result<ShardChunkRead>> {
-            let Some(mut chunk) = self.chunks.pop_front() else {
-                return Poll::Ready(Ok(ShardChunkRead::Eof));
-            };
-            if chunk.len() > max {
-                self.chunks.push_front(chunk.split_off(max));
-                chunk.truncate(max);
-            }
-            Poll::Ready(Ok(ShardChunkRead::Chunk(chunk)))
-        }
-    }
-
-    struct GeneratedChunkSource {
-        bytes: Bytes,
-        offset: usize,
-        fragment_size: usize,
-        fail_at: Option<usize>,
-    }
-
-    impl GeneratedChunkSource {
-        fn new(bytes: Vec<u8>, fragment_size: usize) -> Self {
-            assert!(fragment_size > 0);
-            Self {
-                bytes: Bytes::from(bytes),
-                offset: 0,
-                fragment_size,
-                fail_at: None,
-            }
-        }
-
-        fn failing(bytes: Vec<u8>, fragment_size: usize, fail_at: usize) -> Self {
-            Self {
-                fail_at: Some(fail_at),
-                ..Self::new(bytes, fragment_size)
-            }
-        }
-    }
-
-    impl AsyncRead for GeneratedChunkSource {
-        fn poll_read(self: Pin<&mut Self>, _cx: &mut Context<'_>, _buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
-            Poll::Ready(Err(io::Error::other("generated source must use chunk handoff")))
-        }
-    }
-
-    impl ShardSource for GeneratedChunkSource {
-        fn poll_read_chunk(mut self: Pin<&mut Self>, _cx: &mut Context<'_>, max: usize) -> Poll<io::Result<ShardChunkRead>> {
-            if self.fail_at == Some(self.offset) {
-                return Poll::Ready(Err(rustfs_rio::new_test_internode_http_io_error(
-                    rustfs_rio::InternodeHttpErrorKind::BodyStreamAborted,
-                )));
-            }
-            if self.offset == self.bytes.len() {
-                return Poll::Ready(Ok(ShardChunkRead::Eof));
-            }
-            let error_limit = self.fail_at.unwrap_or(self.bytes.len());
-            let take = self
-                .fragment_size
-                .min(max)
-                .min(error_limit - self.offset)
-                .min(self.bytes.len() - self.offset);
-            let start = self.offset;
-            self.offset += take;
-            Poll::Ready(Ok(ShardChunkRead::Chunk(self.bytes.slice(start..start + take))))
-        }
-    }
-
-    struct InvalidChunkSource {
-        mode: InvalidChunkMode,
-    }
-
-    #[derive(Clone, Copy)]
-    enum InvalidChunkMode {
-        Empty,
-        Oversized,
-        UnsupportedAfterChunk,
-        Unsupported,
-    }
-
-    impl AsyncRead for InvalidChunkSource {
-        fn poll_read(self: Pin<&mut Self>, _cx: &mut Context<'_>, _buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
-            Poll::Ready(Err(io::Error::other("invalid source must use chunk handoff")))
-        }
-    }
-
-    impl ShardSource for InvalidChunkSource {
-        fn poll_read_chunk(mut self: Pin<&mut Self>, _cx: &mut Context<'_>, max: usize) -> Poll<io::Result<ShardChunkRead>> {
-            match self.mode {
-                InvalidChunkMode::Empty => Poll::Ready(Ok(ShardChunkRead::Chunk(Bytes::new()))),
-                InvalidChunkMode::Oversized => Poll::Ready(Ok(ShardChunkRead::Chunk(Bytes::from(vec![0; max + 1])))),
-                InvalidChunkMode::UnsupportedAfterChunk => {
-                    self.mode = InvalidChunkMode::Unsupported;
-                    Poll::Ready(Ok(ShardChunkRead::Chunk(Bytes::from_static(b"x"))))
-                }
-                InvalidChunkMode::Unsupported => Poll::Ready(Ok(ShardChunkRead::Unsupported)),
-            }
-        }
-    }
-
-    struct ScratchReuseSource {
-        block: Option<Bytes>,
-        saw_reused_scratch: bool,
-    }
-
-    impl AsyncRead for ScratchReuseSource {
-        fn poll_read(mut self: Pin<&mut Self>, _cx: &mut Context<'_>, buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
-            let Some(block) = self.block.take() else {
-                return Poll::Ready(Ok(()));
-            };
-            self.saw_reused_scratch = buf.initialize_unfilled()[..block.len()].iter().all(|byte| *byte == 0xa5);
-            buf.put_slice(&block);
-            Poll::Ready(Ok(()))
-        }
-    }
-
-    impl ShardSource for ScratchReuseSource {}
+    use tokio::io::{AsyncWrite, AsyncWriteExt};

    #[derive(Default)]
    struct VectoredCountingWriter {
@@ -1740,70 +1446,6 @@ mod tests {
        assert!(out.is_empty(), "corrupt bytes must never reach the caller's buffer");
    }

-    #[tokio::test]
-    async fn chunked_handoff_verifies_data_split_across_hash_boundaries() {
-        const SHARD: usize = 4096;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let data: Vec<u8> = (0..SHARD).map(|index| (index % 251) as u8).collect();
-        let mut encoded = Vec::new();
-        BitrotWriter::new(&mut encoded, SHARD, algo.clone())
-            .write(&data)
-            .await
-            .expect("write shard");
-
-        let mut output = Vec::with_capacity(SHARD);
-        BitrotReader::new(FragmentedSource::new(encoded, &[3, 11, 19, 37, 128]), SHARD, algo, false)
-            .read_appending(&mut output, SHARD)
-            .await
-            .expect("fragmented shard must verify");
-
-        assert_eq!(output, data);
-    }
-
-    #[tokio::test]
-    async fn chunked_handoff_never_appends_a_corrupt_shard() {
-        const SHARD: usize = 4096;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let mut encoded = Vec::new();
-        BitrotWriter::new(&mut encoded, SHARD, algo.clone())
-            .write(&vec![9u8; SHARD])
-            .await
-            .expect("write shard");
-        let last = encoded.len() - 1;
-        encoded[last] ^= 0xff;
-
-        let mut output = Vec::with_capacity(SHARD);
-        let err = BitrotReader::new(FragmentedSource::new(encoded, &[7, 17, 31]), SHARD, algo, false)
-            .read_appending(&mut output, SHARD)
-            .await
-            .expect_err("corrupt fragmented shard must fail");
-
-        assert_eq!(err.kind(), io::ErrorKind::InvalidData);
-        assert!(output.is_empty());
-    }
-
-    #[tokio::test]
-    async fn chunked_handoff_does_not_hash_when_verification_is_skipped() {
-        const SHARD: usize = 4096;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let mut encoded = Vec::new();
-        BitrotWriter::new(&mut encoded, SHARD, algo.clone())
-            .write(&vec![9u8; SHARD])
-            .await
-            .expect("write shard");
-        encoded[0] ^= 0xff;
-
-        let mut output = Vec::with_capacity(SHARD);
-        let mut reader = BitrotReader::new(FragmentedSource::new(encoded, &[7, 17, 31]), SHARD, algo, true);
-        reader
-            .read_appending(&mut output, SHARD)
-            .await
-            .expect("skipped verification must accept fragmented shard bytes");
-
-        assert_eq!(reader.last_verify_duration(), Duration::ZERO);
-        assert_eq!(output, vec![9u8; SHARD]);
-    }
-
    #[tokio::test]
    async fn read_appending_rejects_a_want_larger_than_the_shard() {
        let algo = HashAlgorithm::HighwayHash256;
@@ -1855,21 +1497,10 @@ mod tests {

        // Equivalence: same bytes out of both paths.
        let mut via_mem: Vec<u8> = Vec::with_capacity(SHARD);
-        let mut memory_reader = BitrotReader::new(Cursor::new(Bytes::from(encoded.clone())), SHARD, algo.clone(), false);
-        memory_reader
+        BitrotReader::new(Cursor::new(Bytes::from(encoded.clone())), SHARD, algo.clone(), false)
            .read_appending(&mut via_mem, SHARD)
            .await
            .expect("in-memory read");
-        assert_eq!(
-            memory_reader.chunks.capacity(),
-            0,
-            "the synchronous fast path must not allocate chunk storage"
-        );
-        assert_eq!(
-            memory_reader.buf.capacity(),
-            0,
-            "the synchronous fast path must not allocate scratch storage"
-        );

        let mut via_stream: Vec<u8> = Vec::with_capacity(SHARD);
        BitrotReader::new(Cursor::new(encoded), SHARD, algo, false)
@@ -1906,152 +1537,4 @@ mod tests {
        assert_eq!(err.kind(), std::io::ErrorKind::InvalidData);
        assert!(out.is_empty(), "corrupt bytes must never reach the caller's buffer");
    }
-
-    #[tokio::test]
-    async fn streaming_fallback_reuses_initialized_scratch() {
-        const SHARD: usize = 4096;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let data = vec![7u8; SHARD];
-        let encoded = encode_one_block(&data, SHARD, algo.clone()).await;
-        let source = ScratchReuseSource {
-            block: Some(Bytes::copy_from_slice(&encoded)),
-            saw_reused_scratch: false,
-        };
-        let mut reader = BitrotReader::new(source, SHARD, algo, false);
-        reader.buf = vec![0xa5; encoded.len()];
-        let mut output = Vec::new();
-
-        reader
-            .read_appending(&mut output, SHARD)
-            .await
-            .expect("streaming fallback should verify");
-
-        assert!(reader.inner.saw_reused_scratch, "capability probing must not clear reusable scratch");
-        assert_eq!(output, data);
-    }
-
-    #[tokio::test]
-    async fn chunked_handoff_bounds_production_sized_one_byte_fragments() {
-        const SHARD: usize = 1024 * 1024 / 4;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let data: Vec<u8> = (0..SHARD).map(|index| (index % 251) as u8).collect();
-        let encoded = encode_one_block(&data, SHARD, algo.clone()).await;
-        let encoded_len = encoded.len();
-        let mut reader = BitrotReader::new(GeneratedChunkSource::new(encoded, 1), SHARD, algo, false);
-        let mut output = Vec::with_capacity(SHARD);
-
-        reader
-            .read_appending(&mut output, SHARD)
-            .await
-            .expect("one-byte fragments should verify with bounded retained state");
-
-        assert_eq!(output, data);
-        assert_eq!(reader.chunks.len(), MAX_RETAINED_CHUNKS_PER_BLOCK);
-        assert!(reader.chunks.capacity() <= MAX_RETAINED_CHUNKS_PER_BLOCK);
-        assert_eq!(reader.buf.len(), encoded_len - MAX_RETAINED_CHUNKS_PER_BLOCK);
-    }
-
-    #[tokio::test]
-    async fn chunked_handoff_keeps_sixty_four_frames_zero_copy_and_respects_poll_budget() {
-        const SHARD: usize = 1024 * 1024;
-        const FRAME: usize = 16 * 1024;
-        let algo = HashAlgorithm::HighwayHash256S;
-
-        let small_data = vec![3u8; 4096];
-        let small_encoded = encode_one_block(&small_data, 4096, algo.clone()).await;
-        let mut exact_reader =
-            BitrotReader::new(FragmentedSource::new(small_encoded.clone(), &[1; 63]), 4096, algo.clone(), false);
-        let mut exact_output = Vec::new();
-        exact_reader
-            .read_appending(&mut exact_output, 4096)
-            .await
-            .expect("exactly sixty-four frames should verify");
-        assert_eq!(exact_output, small_data);
-        assert_eq!(exact_reader.chunks.len(), MAX_RETAINED_CHUNKS_PER_BLOCK);
-        assert!(exact_reader.buf.is_empty(), "the threshold itself must remain zero-copy");
-
-        let mut yielded_reader = BitrotReader::new(FragmentedSource::new(small_encoded, &[1; 65]), 4096, algo.clone(), false);
-        let mut yielded_output = Vec::new();
-        let mut yielded_read = Box::pin(yielded_reader.read_appending(&mut yielded_output, 4096));
-        let mut cx = Context::from_waker(std::task::Waker::noop());
-        assert!(std::future::Future::poll(yielded_read.as_mut(), &mut cx).is_pending());
-        assert!(matches!(std::future::Future::poll(yielded_read.as_mut(), &mut cx), Poll::Ready(Ok(4096))));
-        drop(yielded_read);
-        assert_eq!(yielded_output, small_data);
-
-        let data = vec![7u8; SHARD];
-        let encoded = encode_one_block(&data, SHARD, algo.clone()).await;
-        let mut reader = BitrotReader::new(FragmentedSource::new(encoded, &[FRAME; 64]), SHARD, algo, false);
-        let mut output = Vec::with_capacity(SHARD);
-        let mut read = Box::pin(reader.read_appending(&mut output, SHARD));
-        assert!(
-            matches!(std::future::Future::poll(read.as_mut(), &mut cx), Poll::Ready(Ok(SHARD))),
-            "sixty-five normal HTTP frames should complete without a cooperative yield"
-        );
-        drop(read);
-
-        assert_eq!(output, data);
-        assert_eq!(reader.chunks.len(), MAX_RETAINED_CHUNKS_PER_BLOCK);
-        assert_eq!(reader.buf.len(), HashAlgorithm::HighwayHash256S.size());
-    }
-
-    #[tokio::test]
-    async fn chunked_tail_failures_preserve_errors_and_output() {
-        const SHARD: usize = 4096;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let data = vec![7u8; SHARD];
-        let encoded = encode_one_block(&data, SHARD, algo.clone()).await;
-        let sentinel = vec![1u8, 2, 3];
-
-        let mut short_output = sentinel.clone();
-        let short_err = BitrotReader::new(GeneratedChunkSource::new(encoded[..100].to_vec(), 1), SHARD, algo.clone(), false)
-            .read_appending(&mut short_output, SHARD)
-            .await
-            .expect_err("EOF after the retention threshold must stay a short read");
-        assert_eq!(short_err.kind(), io::ErrorKind::UnexpectedEof);
-        assert_eq!(short_output, sentinel);
-
-        let mut corrupt = encoded.clone();
-        let last = corrupt.len() - 1;
-        corrupt[last] ^= 0xff;
-        let mut corrupt_output = sentinel.clone();
-        let corrupt_err = BitrotReader::new(GeneratedChunkSource::new(corrupt, 1), SHARD, algo.clone(), false)
-            .read_appending(&mut corrupt_output, SHARD)
-            .await
-            .expect_err("corrupt coalesced tail must fail verification");
-        assert_eq!(corrupt_err.kind(), io::ErrorKind::InvalidData);
-        assert_eq!(corrupt_output, sentinel);
-
-        let mut failed_output = sentinel.clone();
-        let body_err = BitrotReader::new(GeneratedChunkSource::failing(encoded, 1, 65), SHARD, algo, false)
-            .read_appending(&mut failed_output, SHARD)
-            .await
-            .expect_err("a terminal body error must not become EOF");
-        let source = body_err
-            .get_ref()
-            .and_then(|source| source.downcast_ref::<rustfs_rio::InternodeHttpError>())
-            .expect("body error should retain internode classification");
-        assert_eq!(source.kind(), rustfs_rio::InternodeHttpErrorKind::BodyStreamAborted);
-        assert_eq!(failed_output, sentinel);
-    }
-
-    #[tokio::test]
-    async fn chunked_handoff_rejects_invalid_source_contracts() {
-        const SHARD: usize = 64;
-        for mode in [
-            InvalidChunkMode::Empty,
-            InvalidChunkMode::Oversized,
-            InvalidChunkMode::UnsupportedAfterChunk,
-        ] {
-            let source = InvalidChunkSource { mode };
-            let mut output = vec![9u8];
-            let err = BitrotReader::new(source, SHARD, HashAlgorithm::HighwayHash256S, false)
-                .read_appending(&mut output, SHARD)
-                .await
-                .expect_err("invalid chunk contracts must fail closed");
-
-            assert_eq!(err.kind(), io::ErrorKind::InvalidData);
-            assert_eq!(output, vec![9u8]);
-        }
-    }
 }
@@ -25,9 +25,7 @@ use crate::disk::error_reduce::reduce_errs;
 use crate::erasure::codec::workspace::ShardBufferPool;
 use crate::erasure::coding::{BitrotReader, Erasure};
 use crate::io_support::bitrot::DeferredReaderStripeHandle;
-use crate::set_disk::shard_source::{
-    INLINE_SHARD_SLOTS, ShardBuffers, ShardErrors, ShardReadCost, ShardStripeSource, StripeReadState,
-};
+use crate::set_disk::shard_source::{ShardReadCost, ShardStripeSource, StripeReadState};
 use futures::FutureExt;
 use futures::stream::{FuturesUnordered, StreamExt};
 use pin_project_lite::pin_project;
@@ -43,6 +41,9 @@ use tracing::{debug, error, warn};

 type ShardReadFuture<'a> = Pin<Box<dyn Future<Output = (usize, ShardReadCost, Result<Vec<u8>, Error>, bool)> + Send + 'a>>;

+const INLINE_SHARD_SLOTS: usize = 32;
+type ShardBuffers = SmallVec<[Option<Vec<u8>>; INLINE_SHARD_SLOTS]>;
+type ShardErrors = SmallVec<[Option<Error>; INLINE_SHARD_SLOTS]>;
 type ShardIndexes = SmallVec<[usize; INLINE_SHARD_SLOTS]>;
 type ActiveReaders = SmallVec<[bool; INLINE_SHARD_SLOTS]>;

@@ -391,7 +392,6 @@ pub(crate) struct ParallelReader<R> {
    // Request-scoped shard buffers keyed by shard index. Keeping ownership in
    // `ParallelReader` avoids dropping unused parity/backup slot buffers between stripes.
    buffers: ShardBufferPool,
-    stripe_state: Option<Box<StripeReadState>>,
    // Lockstep-path state (verify_reconstruction == true). `engaged[i]` marks
    // readers that participate in each stripe read: all data slots from the
    // start, parity slots only once a data shard is missing/dead. Unengaged
@@ -596,7 +596,6 @@ where
            verify_reconstruction,
            locality_preference_enabled: get_shard_locality_preference_enabled(),
            buffers: ShardBufferPool::new(e.data_shards + e.parity_shards),
-            stripe_state: None,
            engaged,
            deferred_handles: Vec::new(),
            stripe_index: 0,
@@ -701,12 +700,6 @@ where
 {
    #[hotpath::measure(impl_type = "ParallelReader")]
    pub async fn read(&mut self) -> StripeReadOutput {
-        let mut state = StripeReadState::with_slot_count(self.readers.len(), self.data_shards);
-        self.read_into_state(&mut state).await;
-        state.into_parts()
-    }
-
-    async fn read_into_state(&mut self, state: &mut StripeReadState) {
        // On the reconstruction-verifying GET path, read every live shard reader
        // in lockstep so all readers advance one block per stripe and stay
        // mutually aligned. The adaptive data-first path below only reads
@@ -716,14 +709,12 @@ where
        // than the data shards, producing "inconsistent read source shards" and
        // truncating large-object GETs under concurrency (backlog#832).
        if self.verify_reconstruction {
-            self.read_lockstep(state).await;
-            return;
+            return self.read_lockstep().await;
        }
        // if self.readers.len() != self.total_shards {
        //     return Err(io::Error::new(ErrorKind::InvalidInput, "Invalid number of readers"));
        // }
        let num_readers = self.readers.len();
-        state.reset(num_readers, self.data_shards);

        let shard_size = if self.offset + self.shard_size > self.shard_file_size {
            self.shard_file_size - self.offset
@@ -732,7 +723,7 @@ where
        };

        if shard_size == 0 {
-            return;
+            return (smallvec![None; num_readers], smallvec![None; num_readers]);
        }

        // Advance to the next stripe so the following read() computes the correct
@@ -743,7 +734,8 @@ where
        // is only read above to derive `shard_size`, so advancing here is safe.
        self.offset += shard_size;

-        let (shards, errs) = state.parts_mut();
+        let mut shards: ShardBuffers = smallvec![None; num_readers];
+        let mut errs: ShardErrors = smallvec![None; num_readers];
        let read_costs = self.read_costs.as_slice();
        let locality_preference_enabled = self.locality_preference_enabled;
        let low_cost_available = self
@@ -890,8 +882,8 @@ where
                }

                let result_is_err = record_shard_read_result(
-                    shards,
-                    errs,
+                    &mut shards,
+                    &mut errs,
                    &mut retire_readers,
                    &mut success,
                    &mut successful_costs,
@@ -952,8 +944,8 @@ where
                    active_readers[i] = false;
                    completed += 1;
                    if record_shard_read_result(
-                        shards,
-                        errs,
+                        &mut shards,
+                        &mut errs,
                        &mut retire_readers,
                        &mut success,
                        &mut successful_costs,
@@ -965,7 +957,7 @@ where
                        failed += 1;
                    }
                }
-                retire_abandoned_readers(errs, &mut retire_readers, &active_readers);
+                retire_abandoned_readers(&mut errs, &mut retire_readers, &active_readers);
            }

            if let Some(path) = self.metrics_path {
@@ -1009,6 +1001,8 @@ where
        for i in retire_readers {
            self.readers[i] = None;
        }
+
+        (shards, errs)
    }

    /// Lockstep stripe read for the reconstruction-verifying GET path.
@@ -1036,18 +1030,18 @@ where
    /// stripe would reintroduce the desync. A parity reader that cannot be
    /// realigned (no pending deferred handle) is likewise retired instead of
    /// being read out of position.
-    async fn read_lockstep(&mut self, state: &mut StripeReadState) {
+    async fn read_lockstep(&mut self) -> StripeReadOutput {
        let num_readers = self.readers.len();
-        state.reset(num_readers, self.data_shards);
        let shard_size = if self.offset + self.shard_size > self.shard_file_size {
            self.shard_file_size - self.offset
        } else {
            self.shard_size
        };

-        let (shards, errs) = state.parts_mut();
+        let mut shards: ShardBuffers = smallvec![None; num_readers];
+        let mut errs: ShardErrors = smallvec![None; num_readers];
        if shard_size == 0 {
-            return;
+            return (shards, errs);
        }

        // Advance to the next stripe (see the matching note in `read`); the
@@ -1285,6 +1279,8 @@ where
        for i in retire_readers {
            self.readers[i] = None;
        }
+
+        (shards, errs)
    }

    /// Attempt to bring an as-yet-unread parity reader into the lockstep read
@@ -1341,20 +1337,10 @@ impl<R> ShardStripeSource for ParallelReader<R>
 where
    R: crate::erasure::coding::ShardSource,
 {
-    async fn read_next_stripe(&mut self) -> Box<StripeReadState> {
-        let mut state = self
-            .stripe_state
-            .take()
-            .unwrap_or_else(|| Box::new(StripeReadState::with_slot_count(self.readers.len(), self.data_shards)));
-        self.read_into_state(&mut state).await;
-        state
-    }
-
-    fn recycle_stripe(&mut self, mut state: Box<StripeReadState>) {
-        self.recycle_shards(state.shards_mut());
-        state.reset(0, self.data_shards);
-        debug_assert!(self.stripe_state.is_none(), "a stripe cannot be recycled twice");
-        self.stripe_state = Some(state);
+    async fn read_next_stripe(&mut self) -> StripeReadState {
+        let read_quorum = self.data_shards;
+        let (shards, errors) = ParallelReader::read(self).await;
+        StripeReadState::from_parts_with_read_costs(shards, errors, &self.read_costs, read_quorum)
    }
 }

@@ -1986,18 +1972,13 @@ mod tests {
    type BoxedShardReader = crate::io_support::bitrot::ShardReader;

    #[test]
-    fn parallel_reader_keeps_stripe_scratch_out_of_line() {
-        eprintln!(
-            "parallel_reader={} stripe_state={} cached_state={}",
-            std::mem::size_of::<ParallelReader<Cursor<Vec<u8>>>>(),
-            std::mem::size_of::<StripeReadState>(),
-            std::mem::size_of::<Option<Box<StripeReadState>>>()
-        );
-        assert_eq!(
-            std::mem::size_of::<Option<Box<StripeReadState>>>(),
-            std::mem::size_of::<usize>(),
-            "the request-scoped cache must remain pointer-sized",
-        );
+    fn shard_scratch_stays_inline_through_the_common_limit_and_spills_safely() {
+        let inline: ShardBuffers = smallvec![None; INLINE_SHARD_SLOTS];
+        assert!(!inline.spilled(), "the common shard-count boundary must not allocate");
+
+        let spilled: ShardBuffers = smallvec![None; INLINE_SHARD_SLOTS + 1];
+        assert!(spilled.spilled(), "larger supported shard counts must fall back to the heap");
+        assert_eq!(spilled.len(), INLINE_SHARD_SLOTS + 1);
    }

    #[tokio::test]
@@ -2016,62 +1997,6 @@ mod tests {
        assert_eq!(errors.len(), TOTAL_SHARDS);
    }

-    #[tokio::test]
-    async fn codec_reader_reuses_inline_and_spilled_stripe_scratch_between_reads() {
-        for total_shards in [INLINE_SHARD_SLOTS, INLINE_SHARD_SLOTS + 1] {
-            let data_shards = total_shards - 1;
-            let readers = std::iter::repeat_with(|| None).take(total_shards).collect();
-            let erasure = Erasure::new(data_shards, 1, data_shards * 2);
-            let mut reader: ParallelReader<Cursor<Vec<u8>>> = ParallelReader::new(readers, erasure, 0, data_shards * 2);
-
-            let first = ShardStripeSource::read_next_stripe(&mut reader).await;
-            let first_state = (&*first) as *const StripeReadState;
-            let first_storage = first.scratch_storage();
-            assert_eq!(first_storage.2, total_shards > INLINE_SHARD_SLOTS);
-            assert_eq!(first_storage.3, total_shards > INLINE_SHARD_SLOTS);
-            ShardStripeSource::recycle_stripe(&mut reader, first);
-
-            let second = ShardStripeSource::read_next_stripe(&mut reader).await;
-            let second_storage = second.scratch_storage();
-
-            assert_eq!(
-                (&*second) as *const StripeReadState,
-                first_state,
-                "the request-scoped state must be reused"
-            );
-            assert_eq!(second_storage.0, first_storage.0, "shard slots must reuse their allocation");
-            assert_eq!(second_storage.1, first_storage.1, "error slots must reuse their allocation");
-            assert_eq!(second.into_parts().0.len(), total_shards);
-        }
-    }
-
-    #[tokio::test]
-    async fn codec_reader_returns_shard_allocations_to_the_request_pool() {
-        const SHARD_SIZE: usize = 16;
-        let hash_algo = HashAlgorithm::None;
-        let readers = vec![Some(create_reader(SHARD_SIZE, 2, 0x5a, &hash_algo, false).await)];
-        let erasure = Erasure::new(1, 0, SHARD_SIZE);
-        let mut reader = ParallelReader::new(readers, erasure, 0, SHARD_SIZE * 2);
-
-        let first = ShardStripeSource::read_next_stripe(&mut reader).await;
-        let first_allocation = first
-            .shard_allocation(0)
-            .expect("the first stripe should own its shard allocation");
-        ShardStripeSource::recycle_stripe(&mut reader, first);
-        assert_eq!(
-            reader.buffers.stored_allocation(0),
-            Some(first_allocation),
-            "recycling a stripe must return its shard allocation to the request pool"
-        );
-
-        let second = ShardStripeSource::read_next_stripe(&mut reader).await;
-        assert_eq!(
-            second.shard_allocation(0),
-            Some(first_allocation),
-            "the next stripe must reuse the pooled shard allocation"
-        );
-    }
-
    /// Counts the raw bytes pulled from a shard stream, to prove which shards
    /// a decode path actually touches (backlog#923 call-count evidence).
    struct CountingShardReader {
@@ -65,7 +65,7 @@ enum FillPolicy {
 }

 impl FillPolicy {
-    fn load() -> Self {
+    fn from_env() -> Self {
        match rustfs_utils::get_env_usize(
            ENV_RUSTFS_GET_CODEC_STREAMING_MAX_INFLIGHT,
            DEFAULT_RUSTFS_GET_CODEC_STREAMING_MAX_INFLIGHT,
@@ -75,22 +75,6 @@ impl FillPolicy {
        }
    }

-    fn from_env() -> Self {
-        #[cfg(test)]
-        {
-            Self::load()
-        }
-        #[cfg(not(test))]
-        {
-            Self::cached_core(Self::load)
-        }
-    }
-
-    fn cached_core(load: impl FnOnce() -> Self) -> Self {
-        static CACHED: std::sync::OnceLock<FillPolicy> = std::sync::OnceLock::new();
-        *CACHED.get_or_init(load)
-    }
-
    const fn max_inflight(self) -> usize {
        match self {
            Self::SingleInFlight => 1,
@@ -495,30 +479,22 @@ where
    let mut deferred_error = None;
    let fill_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
    let stripe_read_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
-    let mut state = source.read_next_stripe().await;
+    let state = source.read_next_stripe().await;
    record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_STRIPE_READ, stripe_read_stage_start);
    let decode_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
    let mut output_buf = reusable_buffers.pop().unwrap_or_default();
-    let result = match decode_stripe_into(
-        metrics_path,
-        stage_metrics_enabled,
-        engine,
-        workspace,
-        &mut state,
-        remaining,
-        &mut output_buf,
-    ) {
-        Ok(true) => Ok(Some(output_buf)),
-        Ok(false) => {
-            reusable_buffers.push(output_buf);
-            Ok(None)
-        }
-        Err(err) => {
-            reusable_buffers.push(output_buf);
-            Err(err)
-        }
-    };
-    source.recycle_stripe(state);
+    let result =
+        match decode_stripe_into(metrics_path, stage_metrics_enabled, engine, workspace, state, remaining, &mut output_buf) {
+            Ok(true) => Ok(Some(output_buf)),
+            Ok(false) => {
+                reusable_buffers.push(output_buf);
+                Ok(None)
+            }
+            Err(err) => {
+                reusable_buffers.push(output_buf);
+                Err(err)
+            }
+        };
    record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_DECODE, decode_stage_start);
    if let Ok(Some(first_buf)) = result.as_ref() {
        let mut remaining_after_first = remaining.saturating_sub(first_buf.len());
@@ -527,7 +503,7 @@ where
                break;
            }
            let stripe_read_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
-            let mut state = source.read_next_stripe().await;
+            let state = source.read_next_stripe().await;
            record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_STRIPE_READ, stripe_read_stage_start);
            let decode_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
            let mut queued_buf = reusable_buffers.pop().unwrap_or_default();
@@ -536,11 +512,10 @@ where
                stage_metrics_enabled,
                engine,
                workspace,
-                &mut state,
+                state,
                remaining_after_first,
                &mut queued_buf,
            );
-            source.recycle_stripe(state);
            record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_DECODE, decode_stage_start);
            match queued_result {
                Ok(true) => {
@@ -742,7 +717,7 @@ fn decode_stripe_into<E>(
    stage_metrics_enabled: bool,
    engine: &E,
    workspace: &mut E::Workspace,
-    state: &mut StripeReadState,
+    state: StripeReadState,
    remaining: usize,
    output: &mut Vec<u8>,
 ) -> io::Result<bool>
@@ -750,7 +725,7 @@ where
    E: ErasureDecodeEngine,
 {
    output.clear();
-    if state.is_empty() {
+    if state.slots().is_empty() {
        return Ok(false);
    }
    if !state.can_decode() {
@@ -766,12 +741,13 @@ where
        );
        record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_RECONSTRUCT, reconstruct_stage_start);
        let emit_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
-        emit_data_shards_into(state, engine.data_shards(), engine.block_size(), remaining, output)?;
+        emit_data_shards_into(&state, engine.data_shards(), engine.block_size(), remaining, output)?;
        record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_EMIT, emit_stage_start);
        return Ok(true);
    }

-    let reconstruct_outcome = match engine.reconstruct_into(state.shards_mut(), workspace) {
+    let (mut shards, _errs) = state.into_parts();
+    let reconstruct_outcome = match engine.reconstruct_into(&mut shards, workspace) {
        Ok(outcome) => outcome,
        Err(err) => {
            record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_RECONSTRUCT, reconstruct_stage_start);
@@ -781,7 +757,7 @@ where
    rustfs_io_metrics::record_get_object_reconstruct_outcome(metrics_path, engine.engine_name(), reconstruct_outcome);
    record_get_stage_duration_if_enabled(metrics_path, GET_STAGE_RECONSTRUCT, reconstruct_stage_start);

-    if state.shards_mut().len() < engine.data_shards() {
+    if shards.len() < engine.data_shards() {
        return Err(io::Error::new(
            ErrorKind::UnexpectedEof,
            "decoded stripe has fewer shards than data shard count",
@@ -790,7 +766,7 @@ where

    let emit_stage_start = get_stage_timer_if_enabled(stage_metrics_enabled);
    reserve_output_capacity(output, engine.block_size().min(remaining));
-    for shard in state.shards_mut().iter().take(engine.data_shards()) {
+    for shard in shards.iter().take(engine.data_shards()) {
        if output.len() >= remaining {
            break;
        }
@@ -830,7 +806,10 @@ fn emit_data_shards_into(
        if output.len() >= remaining {
            break;
        }
-        let Some(shard) = state.data_bytes(index) else {
+        let Some(slot) = state.slot_by_index(index) else {
+            return Err(io::Error::new(ErrorKind::UnexpectedEof, "decoded stripe is missing a data shard"));
+        };
+        let Some(shard) = slot.data_bytes() else {
            return Err(io::Error::new(ErrorKind::UnexpectedEof, "decoded stripe is missing a data shard"));
        };
        let copy_len = shard.len().min(remaining - output.len());
@@ -847,7 +826,7 @@ mod tests {
    };
    use crate::erasure::coding::decode::ParallelReader;
    use crate::erasure::coding::{BitrotReader, BitrotWriter, Erasure};
-    use crate::set_disk::shard_source::StripeReadState;
+    use crate::set_disk::shard_source::{ShardSlot, StripeReadState};
    use rustfs_utils::HashAlgorithm;
    use std::collections::VecDeque;
    use std::future::{pending, poll_fn};
@@ -866,13 +845,6 @@ mod tests {
        read_count: Option<Arc<AtomicUsize>>,
    }

-    struct RecordingStripeSource {
-        stripes: VecDeque<StripeReadState>,
-        read_quorum: usize,
-        reads: usize,
-        recycles: usize,
-    }
-
    struct BlockingSource {
        started: Arc<Notify>,
        dropped: Arc<AtomicUsize>,
@@ -927,43 +899,25 @@ mod tests {

    #[async_trait::async_trait]
    impl ShardStripeSource for VecStripeSource {
-        async fn read_next_stripe(&mut self) -> Box<StripeReadState> {
+        async fn read_next_stripe(&mut self) -> StripeReadState {
            if let Some(read_count) = &self.read_count {
                read_count.fetch_add(1, Ordering::SeqCst);
            }
-            Box::new(
-                self.stripes
-                    .pop_front()
-                    .unwrap_or_else(|| StripeReadState::from_parts(Vec::new(), Vec::new(), self.read_quorum)),
-            )
-        }
-    }
-
-    #[async_trait::async_trait]
-    impl ShardStripeSource for RecordingStripeSource {
-        async fn read_next_stripe(&mut self) -> Box<StripeReadState> {
-            self.reads += 1;
-            Box::new(
-                self.stripes
-                    .pop_front()
-                    .unwrap_or_else(|| StripeReadState::from_parts(Vec::new(), Vec::new(), self.read_quorum)),
-            )
-        }
-
-        fn recycle_stripe(&mut self, _state: Box<StripeReadState>) {
-            self.recycles += 1;
+            self.stripes
+                .pop_front()
+                .unwrap_or_else(|| StripeReadState::new(Vec::new(), self.read_quorum))
        }
    }

    #[async_trait::async_trait]
    impl ShardStripeSource for BlockingSource {
-        async fn read_next_stripe(&mut self) -> Box<StripeReadState> {
+        async fn read_next_stripe(&mut self) -> StripeReadState {
            let _guard = BlockingSourceDropGuard {
                dropped: Arc::clone(&self.dropped),
            };
            self.started.notify_one();
            pending::<()>().await;
-            Box::new(StripeReadState::from_parts(Vec::new(), Vec::new(), self.read_quorum))
+            StripeReadState::new(Vec::new(), self.read_quorum)
        }
    }

@@ -1136,23 +1090,6 @@ mod tests {
        });
    }

-    #[test]
-    fn fill_policy_production_cache_loads_once() {
-        use std::cell::Cell;
-
-        let loads = Cell::new(0);
-        for _ in 0..3 {
-            assert_eq!(
-                FillPolicy::cached_core(|| {
-                    loads.set(loads.get() + 1);
-                    FillPolicy::DualInFlight
-                }),
-                FillPolicy::DualInFlight
-            );
-        }
-        assert_eq!(loads.get(), 1, "the production fill policy must not re-read the environment per reader");
-    }
-
    #[test]
    fn erasure_decode_reader_rejects_invalid_engine_shape() {
        let source = VecStripeSource {
@@ -1752,10 +1689,7 @@ mod tests {
            .pop_front()
            .expect("first stripe should exist");
        let mut source = VecStripeSource {
-            stripes: VecDeque::from([
-                first_state,
-                StripeReadState::from_parts(Vec::new(), Vec::new(), erasure.data_shards),
-            ]),
+            stripes: VecDeque::from([first_state, StripeReadState::new(Vec::new(), erasure.data_shards)]),
            read_quorum: erasure.data_shards,
            read_count: None,
        };
@@ -1790,14 +1724,13 @@ mod tests {
            .stripes
            .pop_front()
            .expect("first stripe should exist");
-        let mut source = RecordingStripeSource {
+        let mut source = VecStripeSource {
            stripes: VecDeque::from([
                first_state,
-                StripeReadState::from_parts(vec![Some(vec![1])], Vec::new(), erasure.data_shards),
+                StripeReadState::new(vec![ShardSlot::data(0, vec![1])], erasure.data_shards),
            ]),
            read_quorum: erasure.data_shards,
-            reads: 0,
-            recycles: 0,
+            read_count: None,
        };
        let engine = LegacyEcDecodeEngine::new(erasure);
        let mut workspace = engine.prepare_workspace(4).expect("workspace should be prepared");
@@ -1823,8 +1756,6 @@ mod tests {
                .kind(),
            ErrorKind::Other
        );
-        assert_eq!(source.reads, 2, "the fill must read the primary and queued stripe");
-        assert_eq!(source.recycles, source.reads, "every completed stripe read must be recycled");
    }

    #[tokio::test]
@@ -1837,7 +1768,7 @@ mod tests {
                    .stripes
                    .pop_front()
                    .expect("first stripe should exist"),
-                StripeReadState::from_parts(Vec::new(), Vec::new(), erasure.data_shards),
+                StripeReadState::new(Vec::new(), erasure.data_shards),
            ]),
            read_quorum: erasure.data_shards,
            read_count: None,
@@ -2097,11 +2028,17 @@ mod tests {
    }

    #[test]
-    fn emit_data_shards_preserves_output_order() {
-        let state =
-            StripeReadState::from_parts(vec![Some(b"ab".to_vec()), Some(b"cd".to_vec()), Some(b"ef".to_vec())], Vec::new(), 2);
+    fn emit_data_shards_preserves_output_order_for_out_of_order_slots() {
+        let state = StripeReadState::new(
+            vec![
+                ShardSlot::data(1, b"cd".to_vec()),
+                ShardSlot::data(0, b"ab".to_vec()),
+                ShardSlot::data(2, b"ef".to_vec()),
+            ],
+            2,
+        );

-        let output = emit_data_shards(&state, 3, 6, 5).expect("data slots should emit by shard index");
+        let output = emit_data_shards(&state, 3, 6, 5).expect("out-of-order data slots should emit by shard index");

        assert_eq!(output, b"abcde");
    }
@@ -2114,27 +2051,27 @@ mod tests {
        };
        let mut workspace = engine.prepare_workspace(4).expect("workspace should be prepared");
        let mut output = Vec::with_capacity(1);
-        let mut short_state = StripeReadState::from_parts(vec![Some(vec![1, 2, 3, 4])], Vec::new(), 1);
+        let short_state = StripeReadState::new(vec![ShardSlot::data(0, vec![1, 2, 3, 4])], 1);

        let err = decode_stripe_into(
            GET_OBJECT_PATH_CODEC_STREAMING,
            false,
            &engine,
            &mut workspace,
-            &mut short_state,
+            short_state,
            8,
            &mut output,
        )
        .expect_err("decoded stripe shorter than data shard count must fail");
        assert_eq!(err.kind(), ErrorKind::UnexpectedEof);

-        let mut missing_state = StripeReadState::from_parts(vec![None, Some(vec![5, 6, 7, 8])], Vec::new(), 1);
+        let missing_state = StripeReadState::from_parts(vec![None, Some(vec![5, 6, 7, 8])], Vec::new(), 1);
        let err = decode_stripe_into(
            GET_OBJECT_PATH_CODEC_STREAMING,
            false,
            &engine,
            &mut workspace,
-            &mut missing_state,
+            missing_state,
            8,
            &mut output,
        )
@@ -2145,35 +2082,6 @@ mod tests {
        assert!(output.capacity() >= 32);
    }

-    #[test]
-    fn decode_stripe_reconstructs_in_place_without_replacing_slot_storage() {
-        let erasure = Erasure::new(2, 1, 8);
-        let engine = LegacyEcDecodeEngine::new(erasure.clone());
-        let mut workspace = engine.prepare_workspace(4).expect("workspace should be prepared");
-        let encoded = erasure.encode_data(b"abcdefgh").expect("test stripe should encode");
-        let mut shards = encoded.into_iter().map(|shard| Some(shard.to_vec())).collect::<Vec<_>>();
-        shards[0] = None;
-        let mut state = StripeReadState::from_parts(shards, vec![Some(DiskError::FileCorrupt)], 2);
-        let before = state.scratch_storage();
-        let mut output = Vec::new();
-
-        let decoded = decode_stripe_into(
-            GET_OBJECT_PATH_CODEC_STREAMING,
-            false,
-            &engine,
-            &mut workspace,
-            &mut state,
-            8,
-            &mut output,
-        )
-        .expect("degraded stripe should reconstruct");
-
-        assert!(decoded);
-        assert_eq!(output, b"abcdefgh");
-        assert_eq!(state.scratch_storage().0, before.0, "reconstruction must retain shard slot storage");
-        assert_eq!(state.scratch_storage().1, before.1, "unused error storage must not be rebuilt");
-    }
-
    #[tokio::test]
    async fn erasure_decode_reader_reports_short_source() {
        let erasure = Erasure::new(4, 2, 32);
@@ -18,12 +18,10 @@ use crate::disk::error_reduce::{
 };
 use crate::erasure::coding::BitrotWriterWrapper;
 use crate::erasure::coding::Erasure;
-use crate::erasure::coding::erasure::EncodedBlock;
 use crate::runtime::sources as runtime_sources;
 use bytes::{Bytes, BytesMut};
 use futures::StreamExt;
 use futures::stream::FuturesUnordered;
-use rustfs_utils::HashAlgorithm;
 use std::sync::Arc;
 use std::time::Instant;
 use std::vec;
@@ -225,8 +223,8 @@ async fn send_queued<T>(
    sender.send(InflightEntry::new(entry, bytes)).await
 }

-fn queued_batch_bytes(batch: &[EncodedBlock]) -> usize {
-    batch.iter().map(EncodedBlock::queued_bytes).sum()
+fn queued_batch_bytes(batch: &[Vec<Bytes>]) -> usize {
+    batch.iter().map(|block| queued_block_bytes(block)).sum()
 }

 fn dominant_error_summary_label(summary: &WriteQuorumFailureSummary) -> &'static str {
@@ -338,7 +336,7 @@ impl<'a> MultiWriter<'a> {
        }
    }

-    async fn write_shard(writer_opt: &mut Option<BitrotWriterWrapper>, err: &mut Option<Error>, shard: &[u8]) {
+    async fn write_shard(writer_opt: &mut Option<BitrotWriterWrapper>, err: &mut Option<Error>, shard: &Bytes) {
        match writer_opt {
            Some(writer) => {
                match writer.write(shard).await {
@@ -363,20 +361,12 @@ impl<'a> MultiWriter<'a> {
    }

    pub async fn write(&mut self, data: Vec<Bytes>) -> std::io::Result<()> {
-        self.write_shards(data.iter().map(Bytes::as_ref)).await
-    }
-
-    async fn write_block(&mut self, block: &EncodedBlock) -> std::io::Result<()> {
-        self.write_shards(block.shards()).await
-    }
-
-    async fn write_shards<'b>(&mut self, shards: impl ExactSizeIterator<Item = &'b [u8]>) -> std::io::Result<()> {
-        assert_eq!(shards.len(), self.writers.len());
+        assert_eq!(data.len(), self.writers.len());

        let budget = self.next_progress_budget();
        {
            let mut futures = FuturesUnordered::new();
-            for ((writer_opt, err), shard) in self.writers.iter_mut().zip(self.errs.iter_mut()).zip(shards) {
+            for ((writer_opt, err), shard) in self.writers.iter_mut().zip(self.errs.iter_mut()).zip(data.iter()) {
                if err.is_some() {
                    continue; // Skip if we already have an error for this writer
                }
@@ -500,10 +490,10 @@ impl<'a> MultiWriter<'a> {
 }

 impl Erasure {
-    async fn encode_block(self: Arc<Self>, encode_buf: Vec<u8>, len: usize) -> std::io::Result<(EncodedBlock, Vec<u8>)> {
+    async fn encode_block(self: Arc<Self>, encode_buf: Vec<u8>, len: usize) -> std::io::Result<(Vec<Bytes>, Vec<u8>)> {
        let encode_stage_start = stage_timer_if_enabled();
        let encode_once = move || {
-            let res = self.encode_data_block(&encode_buf[..len]);
+            let res = self.encode_data(&encode_buf[..len]);
            (res, encode_buf)
        };

@@ -528,9 +518,9 @@ impl Erasure {
        Ok((res?, returned_buf))
    }

-    async fn encode_block_bytes_mut(self: Arc<Self>, encode_buf: BytesMut, len: usize) -> std::io::Result<EncodedBlock> {
+    async fn encode_block_bytes_mut(self: Arc<Self>, encode_buf: BytesMut, len: usize) -> std::io::Result<Vec<Bytes>> {
        let encode_stage_start = stage_timer_if_enabled();
-        let encode_once = move || self.encode_data_bytes_mut_block(encode_buf, len);
+        let encode_once = move || self.encode_data_bytes_mut(encode_buf, len);

        let res = match tokio::runtime::Handle::current().runtime_flavor() {
            // Same rationale as encode_block: inline the short EC burst on the
@@ -586,46 +576,13 @@ impl Erasure {
            ));
        }

-        let block = self.encode_data_owned_block(buf)?;
+        let shards = self.encode_data_owned(buf)?;
        let mut mw = MultiWriter::new(writers, quorum);
-        mw.write_block(&block).await?;
+        mw.write(shards).await?;
        mw.shutdown().await?;
        Ok((reader, total))
    }

-    /// Encode a small inline object directly into its per-disk bitrot payloads.
-    /// The returned bytes are the same `[hash][shard]` representation produced
-    /// by `BitrotWriter`, ready to be embedded in each disk's staged `xl.meta`.
-    #[hotpath::measure(impl_type = "Erasure")]
-    pub(crate) async fn encode_inline_shards_with_size_hint<R>(
-        self: Arc<Self>,
-        mut reader: R,
-        size_hint: usize,
-    ) -> std::io::Result<(R, usize, Vec<Bytes>)>
-    where
-        R: AsyncRead + Send + Sync + Unpin,
-    {
-        use tokio::io::AsyncReadExt;
-
-        let mut buf = Vec::with_capacity(small_ingest_capacity(&self, size_hint));
-        let total = reader.read_to_end(&mut buf).await?;
-        if total == 0 {
-            return Ok((reader, 0, Vec::new()));
-        }
-
-        let block = self.encode_data_owned_block(buf)?;
-        let mut inline_shards = Vec::with_capacity(block.shards().len());
-        for shard in block.shards() {
-            let hash = HashAlgorithm::HighwayHash256S.hash_encode(shard);
-            let mut encoded = BytesMut::with_capacity(hash.as_ref().len() + shard.len());
-            encoded.extend_from_slice(hash.as_ref());
-            encoded.extend_from_slice(shard);
-            inline_shards.push(encoded.freeze());
-        }
-
-        Ok((reader, total, inline_shards))
-    }
-
    #[hotpath::measure(impl_type = "Erasure")]
    pub async fn encode<R>(
        self: Arc<Self>,
@@ -667,7 +624,7 @@ impl Erasure {
        let expanded_block_bytes = self.shard_size().saturating_mul(self.total_shard_count());
        let max_inflight_bytes = erasure_encode_max_inflight_bytes();
        let inflight_blocks = encode_channel_capacity(expanded_block_bytes, max_inflight_bytes);
-        let (tx, mut rx) = mpsc::channel::<InflightEntry<EncodedBlock>>(inflight_blocks);
+        let (tx, mut rx) = mpsc::channel::<InflightEntry<Vec<Bytes>>>(inflight_blocks);

        let mut task = AbortOnDropTask::new(tokio::spawn(async move {
            let block_size = self.block_size;
@@ -689,7 +646,7 @@ impl Erasure {
                            let encode_buf = buf;
                            let res = self.clone().encode_block_bytes_mut(encode_buf, n).await?;
                            buf = BytesMut::with_capacity(ingest_capacity);
-                            let queued_bytes = res.queued_bytes();
+                            let queued_bytes = queued_block_bytes(&res);
                            let _producer_stage = rustfs_io_metrics::track_ec_encode_producer_bytes(queued_bytes);
                            let send_wait_stage_start = stage_timer_if_enabled();
                            if let Err(err) = send_queued(&tx, res, queued_bytes).await {
@@ -719,7 +676,7 @@ impl Erasure {
                            let encode_buf = std::mem::take(&mut buf);
                            let (res, returned_buf) = self.clone().encode_block(encode_buf, n).await?;
                            buf = returned_buf;
-                            let queued_bytes = res.queued_bytes();
+                            let queued_bytes = queued_block_bytes(&res);
                            let _producer_stage = rustfs_io_metrics::track_ec_encode_producer_bytes(queued_bytes);
                            let send_wait_stage_start = stage_timer_if_enabled();
                            if let Err(err) = send_queued(&tx, res, queued_bytes).await {
@@ -763,9 +720,9 @@ impl Erasure {
            if block.is_empty() {
                break;
            }
-            let _writer_stage = rustfs_io_metrics::track_ec_encode_writer_bytes(block.queued_bytes());
+            let _writer_stage = rustfs_io_metrics::track_ec_encode_writer_bytes(queued_block_bytes(&block));
            let write_stage_start = stage_timer_if_enabled();
-            if let Err(err) = writers.write_block(&block).await {
+            if let Err(err) = writers.write(block).await {
                write_err = Some(err);
                break;
            }
@@ -812,7 +769,7 @@ impl Erasure {
        let inflight_blocks = encode_channel_capacity(expanded_block_bytes, max_inflight_bytes);
        let batch_blocks = encode_batch_block_count().min(inflight_blocks);
        let channel_capacity = inflight_blocks.div_ceil(batch_blocks).max(1);
-        let (tx, mut rx) = mpsc::channel::<InflightEntry<Vec<EncodedBlock>>>(channel_capacity);
+        let (tx, mut rx) = mpsc::channel::<InflightEntry<Vec<Vec<Bytes>>>>(channel_capacity);

        let mut task = AbortOnDropTask::new(tokio::spawn(async move {
            let block_size = self.block_size;
@@ -829,7 +786,7 @@ impl Erasure {
                        let encode_buf = std::mem::take(&mut buf);
                        let (res, returned_buf) = self.clone().encode_block(encode_buf, n).await?;
                        buf = returned_buf;
-                        let queued_bytes = res.queued_bytes();
+                        let queued_bytes = queued_block_bytes(&res);
                        pending_batch_bytes = pending_batch_bytes.saturating_add(queued_bytes);
                        pending_batch.push(res);
                        drop(pending_batch_stage.take());
@@ -888,7 +845,7 @@ impl Erasure {
            let _writer_stage = rustfs_io_metrics::track_ec_encode_writer_bytes(queued_batch_bytes(&batch));
            let write_stage_start = stage_timer_if_enabled();
            for block in batch {
-                if let Err(err) = writers.write_block(&block).await {
+                if let Err(err) = writers.write(block).await {
                    write_err = Some(err);
                    break;
                }
@@ -1938,11 +1895,7 @@ mod tests {
        let baseline = rustfs_io_metrics::current_ec_encode_inflight_bytes();
        let (tx, rx) = mpsc::channel(2);
        let mut rx = rx;
-        let erasure = Erasure::new(1, 0, 16);
-        let batch = vec![
-            erasure.encode_data_block(b"queued").expect("first block should encode"),
-            erasure.encode_data_block(b"batch").expect("second block should encode"),
-        ];
+        let batch = vec![vec![Bytes::from_static(b"queued")], vec![Bytes::from_static(b"batch")]];
        let batch_bytes = queued_batch_bytes(&batch);

        send_queued(&tx, batch, batch_bytes).await.expect("batch should be queued");
@@ -2164,39 +2117,6 @@ mod tests {
        );
    }

-    #[tokio::test]
-    async fn cancelling_inline_small_drops_stalled_write() {
-        const BLOCK_SIZE: usize = 16;
-
-        let (writer_entered_tx, writer_entered) = oneshot::channel();
-        let writes = Arc::new(std::sync::atomic::AtomicUsize::new(0));
-        let mut writers = vec![Some(bitrot_writer_plain(
-            StallOnWriteWithSignal {
-                entered: Some(writer_entered_tx),
-                writes: writes.clone(),
-            },
-            BLOCK_SIZE,
-        ))];
-        let erasure = Arc::new(Erasure::new(1, 0, BLOCK_SIZE));
-        let reader = tokio::io::BufReader::new(Cursor::new(vec![0xA5; BLOCK_SIZE - 1]));
-        let encode = tokio::spawn(async move { erasure.encode_inline_small(reader, &mut writers, 1).await });
-
-        tokio::time::timeout(Duration::from_secs(1), writer_entered)
-            .await
-            .expect("inline writer should enter before cancellation")
-            .expect("stalling writer should signal entry");
-        encode.abort();
-        assert!(
-            matches!(encode.await, Err(err) if err.is_cancelled()),
-            "inline encode task should be cancelled"
-        );
-        assert_eq!(
-            writes.load(std::sync::atomic::Ordering::SeqCst),
-            1,
-            "cancellation must drop the stalled write instead of polling it again"
-        );
-    }
-
    #[tokio::test]
    async fn encode_returns_unexpected_eof_for_truncated_limited_reader() {
        let committed = Arc::new(Mutex::new(Vec::new()));
@@ -2316,11 +2236,11 @@ mod tests {
            .expect("bytesmut encode should succeed on current-thread runtime");

        let expected_shard_size = payload.len().div_ceil(erasure.data_shards);
-        assert_eq!(shards.shards().len(), erasure.total_shard_count());
-        assert!(shards.shards().all(|shard| shard.len() == expected_shard_size));
+        assert_eq!(shards.len(), erasure.total_shard_count());
+        assert!(shards.iter().all(|shard| shard.len() == expected_shard_size));

        let mut restored = Vec::new();
-        for shard in shards.shards().take(erasure.data_shards) {
+        for shard in shards.iter().take(erasure.data_shards) {
            restored.extend_from_slice(shard);
        }
        restored.truncate(payload.len());
@@ -2423,41 +2343,6 @@ mod tests {
        assert!(committed.lock().unwrap().is_empty());
    }

-    #[tokio::test]
-    async fn encode_inline_shards_matches_writer_bitrot_layout() {
-        const DATA_SHARDS: usize = 2;
-        const PARITY_SHARDS: usize = 2;
-        const BLOCK_SIZE: usize = 64;
-        let checksum_algo = HashAlgorithm::HighwayHash256S;
-        for uses_legacy in [false, true] {
-            let erasure = Arc::new(Erasure::new_with_options(DATA_SHARDS, PARITY_SHARDS, BLOCK_SIZE, uses_legacy));
-            for payload in [Vec::new(), vec![0xA5], vec![0x5A; BLOCK_SIZE - 1], vec![0xC3; BLOCK_SIZE]] {
-                let reader = tokio::io::BufReader::new(Cursor::new(payload.clone()));
-                let (_reader, total, inline_shards) = erasure
-                    .clone()
-                    .encode_inline_shards_with_size_hint(reader, payload.len())
-                    .await
-                    .expect("inline shards should encode");
-
-                assert_eq!(total, payload.len());
-                if payload.is_empty() {
-                    assert!(inline_shards.is_empty());
-                    continue;
-                }
-
-                let raw_shards = erasure.encode_data(&payload).expect("reference shards should encode");
-                assert_eq!(inline_shards.len(), DATA_SHARDS + PARITY_SHARDS);
-                for (inline, raw) in inline_shards.iter().zip(raw_shards) {
-                    let mut writer =
-                        BitrotWriterWrapper::new(CustomWriter::new_inline_buffer(), raw.len(), checksum_algo.clone());
-                    writer.write(&raw).await.expect("reference writer should accept shard");
-                    writer.shutdown().await.expect("reference writer should shutdown");
-                    assert_eq!(inline.as_ref(), writer.into_inline_data().expect("reference writer should retain bytes"));
-                }
-            }
-        }
-    }
-
    /// encode_inline_small: small payload is encoded into the correct number of shards
    /// and each writer receives data after shutdown.
    #[tokio::test]
@@ -2621,7 +2506,7 @@ mod tests {
        assert_eq!(&next[..], &data[16..]);
    }

-    async fn committed_shards_for_pipeline(pipeline: EncodePipeline, uses_legacy: bool, payload: &[u8]) -> Vec<Vec<u8>> {
+    async fn committed_shards_for_ingest_mode(use_bytesmut_ingest: bool, uses_legacy: bool, payload: &[u8]) -> Vec<Vec<u8>> {
        const DATA_SHARDS: usize = 2;
        const PARITY_SHARDS: usize = 2;
        const TOTAL_SHARDS: usize = DATA_SHARDS + PARITY_SHARDS;
@@ -2635,16 +2520,10 @@ mod tests {

        let erasure = Arc::new(Erasure::new_with_options(DATA_SHARDS, PARITY_SHARDS, BLOCK_SIZE, uses_legacy));
        let reader = tokio::io::BufReader::new(Cursor::new(payload.to_vec()));
-        let (_reader, total) = match pipeline {
-            EncodePipeline::Vec => {
-                erasure
-                    .encode_with_ingest_mode(reader, &mut writers, DATA_SHARDS, false)
-                    .await
-            }
-            EncodePipeline::BytesMut => erasure.encode_with_ingest_mode(reader, &mut writers, DATA_SHARDS, true).await,
-            EncodePipeline::Batched => erasure.encode_batched(reader, &mut writers, DATA_SHARDS).await,
-        }
-        .expect("encode should succeed");
+        let (_reader, total) = erasure
+            .encode_with_ingest_mode(reader, &mut writers, DATA_SHARDS, use_bytesmut_ingest)
+            .await
+            .expect("encode should succeed");
        assert_eq!(total, payload.len());

        committed
@@ -2653,64 +2532,31 @@ mod tests {
            .collect()
    }

-    async fn expected_committed_shards(uses_legacy: bool, payload: &[u8]) -> Vec<Vec<u8>> {
-        const DATA_SHARDS: usize = 2;
-        const PARITY_SHARDS: usize = 2;
-        const TOTAL_SHARDS: usize = DATA_SHARDS + PARITY_SHARDS;
-        const BLOCK_SIZE: usize = 64;
-
-        let committed: Vec<Arc<Mutex<Vec<u8>>>> = (0..TOTAL_SHARDS).map(|_| Arc::new(Mutex::new(Vec::new()))).collect();
-        let mut writers: Vec<BitrotWriterWrapper> = committed
-            .iter()
-            .map(|c| bitrot_writer(DeferredCommitWriter::new(c.clone()), BLOCK_SIZE / DATA_SHARDS))
-            .collect();
-        let erasure = Erasure::new_with_options(DATA_SHARDS, PARITY_SHARDS, BLOCK_SIZE, uses_legacy);
-
-        for block in payload.chunks(BLOCK_SIZE) {
-            let shards = erasure.encode_data(block).expect("reference block should encode");
-            for (writer, shard) in writers.iter_mut().zip(shards) {
-                let written = writer.write(&shard).await.expect("reference shard should write");
-                assert_eq!(written, shard.len());
-            }
-        }
-        for writer in &mut writers {
-            writer.shutdown().await.expect("reference writer should commit");
-        }
-
-        committed
-            .iter()
-            .map(|c| c.lock().expect("committed buffer should be lockable").clone())
-            .collect()
-    }
-
-    /// The streaming and batched paths must produce the same bitrot-wrapped shard
-    /// bytes as the public block encoder for both shard-size formulas and all block
-    /// boundary shapes.
+    /// HP-10 (rustfs/backlog#931) merge gate: the BytesMut ingest path must produce
+    /// byte-for-byte identical shard streams to the default Vec ingest path, for both
+    /// legacy-aware shard-size formulas, across empty, sub-block, exactly-full-block,
+    /// and multi-block-with-partial-tail payloads.
    #[tokio::test]
    async fn bytesmut_ingest_matches_vec_ingest_byte_for_byte() {
        const BLOCK_SIZE: usize = 64;
        let payloads: Vec<Vec<u8>> = vec![
            Vec::new(),
-            vec![1],
-            vec![2; BLOCK_SIZE - 1],
+            b"tiny".to_vec(),
            (0..BLOCK_SIZE as u32).map(|i| i as u8).collect(), // exactly one full block
-            vec![4; BLOCK_SIZE + 1],
-            vec![3u8; BLOCK_SIZE * 4],                                           // whole number of blocks
+            vec![3u8; BLOCK_SIZE * 4],                         // whole number of blocks
            (0..(BLOCK_SIZE * 3 + 7) as u32).map(|i| (i % 251) as u8).collect(), // partial tail
        ];

        for uses_legacy in [false, true] {
            for payload in &payloads {
-                let expected = expected_committed_shards(uses_legacy, payload).await;
-                for pipeline in [EncodePipeline::Vec, EncodePipeline::BytesMut, EncodePipeline::Batched] {
-                    let actual = committed_shards_for_pipeline(pipeline, uses_legacy, payload).await;
-                    assert_eq!(
-                        actual,
-                        expected,
-                        "streaming shards must match the public block encoder (legacy={uses_legacy}, payload_len={})",
-                        payload.len()
-                    );
-                }
+                let vec_path = committed_shards_for_ingest_mode(false, uses_legacy, payload).await;
+                let bytesmut_path = committed_shards_for_ingest_mode(true, uses_legacy, payload).await;
+                assert_eq!(
+                    vec_path,
+                    bytesmut_path,
+                    "ingest paths must be byte-identical (legacy={uses_legacy}, payload_len={})",
+                    payload.len()
+                );
            }
        }
    }
@@ -29,58 +29,12 @@ use tokio::io::AsyncRead;
 use tracing::warn;
 use uuid::Uuid;

-pub(crate) struct EncodedBlock {
-    data: Bytes,
-    shard_size: usize,
-}
-
-impl EncodedBlock {
-    fn empty() -> Self {
-        Self {
-            data: Bytes::new(),
-            shard_size: 0,
-        }
-    }
-
-    pub(crate) fn is_empty(&self) -> bool {
-        self.data.is_empty()
-    }
-
-    pub(crate) fn queued_bytes(&self) -> usize {
-        self.data.len()
-    }
-
-    pub(crate) fn shards(&self) -> impl ExactSizeIterator<Item = &[u8]> {
-        debug_assert!(self.shard_size > 0, "only non-empty encoded blocks reach shard writers");
-        debug_assert_eq!(self.data.len() % self.shard_size, 0);
-        self.data.chunks_exact(self.shard_size)
-    }
-
-    fn into_shards(mut self, shard_count: usize) -> Vec<Bytes> {
-        if self.shard_size == 0 {
-            return vec![Bytes::new(); shard_count];
-        }
-
-        let mut shards = Vec::with_capacity(shard_count);
-        for _ in 0..shard_count {
-            shards.push(self.data.split_to(self.shard_size));
-        }
-        shards
-    }
-}
-
 const MODERN_MAX_TOTAL_SHARDS: usize = <reed_solomon_erasure::galois_8::Field as reed_solomon_erasure::Field>::ORDER;
 const MODERN_REED_SOLOMON_CACHE_MAX_ENTRIES: usize = 64;
-const LEGACY_REED_SOLOMON_CACHE_MAX_ENTRIES: usize = 16;
-// Vec growth may retain twice the requested logical length. Keeping the logical
-// workspace at half the budget bounds each cached workspace's shard allocation to 1 MiB.
-const LEGACY_REED_SOLOMON_CACHE_MAX_LOGICAL_SHARD_BYTES_PER_WORKSPACE: usize = 512 * 1024;

 type ModernReedSolomonCache = RwLock<HashMap<(usize, usize), Arc<ReedSolomon>>>;
-type LegacyReedSolomonCache = RwLock<HashMap<(usize, usize), Arc<LegacyReedSolomonEncoder>>>;

 static MODERN_REED_SOLOMON_CACHE: OnceLock<ModernReedSolomonCache> = OnceLock::new();
-static LEGACY_REED_SOLOMON_CACHE: OnceLock<LegacyReedSolomonCache> = OnceLock::new();

 /// Errors returned when constructing an [`Erasure`] codec.
 #[derive(Debug, thiserror::Error)]
@@ -147,61 +101,43 @@ pub fn calc_shard_size_legacy(block_size: usize, data_shards: usize) -> usize {
 struct LegacyReedSolomonEncoder {
    data_shards: usize,
    parity_shards: usize,
-    cache_workspaces: bool,
-    encoder_cache: RwLock<Option<reed_solomon_simd::ReedSolomonEncoder>>,
-    decoder_cache: RwLock<Option<reed_solomon_simd::ReedSolomonDecoder>>,
+    encoder_cache: std::sync::RwLock<Option<reed_solomon_simd::ReedSolomonEncoder>>,
+    decoder_cache: std::sync::RwLock<Option<reed_solomon_simd::ReedSolomonDecoder>>,
+}
+
+impl Clone for LegacyReedSolomonEncoder {
+    fn clone(&self) -> Self {
+        Self {
+            data_shards: self.data_shards,
+            parity_shards: self.parity_shards,
+            encoder_cache: std::sync::RwLock::new(None),
+            decoder_cache: std::sync::RwLock::new(None),
+        }
+    }
 }

 impl LegacyReedSolomonEncoder {
-    fn new(data_shards: usize, parity_shards: usize) -> io::Result<Self> {
-        Self::with_workspace_cache(data_shards, parity_shards, false)
-    }
-
-    fn with_workspace_cache(data_shards: usize, parity_shards: usize, cache_workspaces: bool) -> io::Result<Self> {
+    fn new(_data_shards: usize, _parity_shards: usize) -> io::Result<Self> {
        Ok(Self {
-            data_shards,
-            parity_shards,
-            cache_workspaces,
-            encoder_cache: RwLock::new(None),
-            decoder_cache: RwLock::new(None),
+            data_shards: _data_shards,
+            parity_shards: _parity_shards,
+            encoder_cache: std::sync::RwLock::new(None),
+            decoder_cache: std::sync::RwLock::new(None),
        })
    }

-    fn logical_shard_bytes_upper_bound(&self, shard_len: usize) -> Option<usize> {
-        let aligned_shard_len = shard_len.checked_add(63)?.checked_div(64)?.checked_mul(64)?;
-        let high_rate_decoder_work_count = self
-            .parity_shards
-            .checked_next_power_of_two()?
-            .checked_add(self.data_shards)?
-            .checked_next_power_of_two()?;
-        let low_rate_decoder_work_count = self
-            .data_shards
-            .checked_next_power_of_two()?
-            .checked_add(self.parity_shards)?
-            .checked_next_power_of_two()?;
-        aligned_shard_len.checked_mul(high_rate_decoder_work_count.max(low_rate_decoder_work_count))
-    }
-
-    fn should_cache_workspace(&self, shard_len: usize) -> bool {
-        self.cache_workspaces
-            && self
-                .logical_shard_bytes_upper_bound(shard_len)
-                .is_some_and(|bytes| bytes <= LEGACY_REED_SOLOMON_CACHE_MAX_LOGICAL_SHARD_BYTES_PER_WORKSPACE)
-    }
-
    fn encode(&self, shards: SmallVec<[&mut [u8]; 16]>) -> io::Result<()> {
        let mut shards_vec: Vec<&mut [u8]> = shards.into_vec();
        if shards_vec.is_empty() {
            return Ok(());
        }
        let shard_len = shards_vec[0].len();
-        let cached_encoder = self
-            .encoder_cache
-            .write()
-            .map_err(|_| io::Error::other("Failed to acquire encoder cache lock"))?
-            .take();
        let mut encoder = {
-            match cached_encoder {
+            let mut cache_guard = self
+                .encoder_cache
+                .write()
+                .map_err(|_| io::Error::other("Failed to acquire encoder cache lock"))?;
+            match cache_guard.take() {
                Some(mut cached) => {
                    if cached.reset(self.data_shards, self.parity_shards, shard_len).is_err() {
                        reed_solomon_simd::ReedSolomonEncoder::new(self.data_shards, self.parity_shards, shard_len)
@@ -228,15 +164,10 @@ impl LegacyReedSolomonEncoder {
            }
        }
        drop(result);
-        if self.should_cache_workspace(shard_len) {
-            let mut cache = self
-                .encoder_cache
-                .write()
-                .map_err(|_| io::Error::other("Failed to return encoder to cache"))?;
-            if cache.is_none() {
-                *cache = Some(encoder);
-            }
-        }
+        *self
+            .encoder_cache
+            .write()
+            .map_err(|_| io::Error::other("Failed to return encoder to cache"))? = Some(encoder);
        Ok(())
    }

@@ -250,13 +181,13 @@ impl LegacyReedSolomonEncoder {
            .find_map(|s| s.as_ref().map(|v| v.len()))
            .ok_or_else(|| io::Error::other("No valid shards found for reconstruction"))?;

-        let cached_decoder = self
-            .decoder_cache
-            .write()
-            .map_err(|_| io::Error::other("Failed to acquire decoder cache lock"))?
-            .take();
        let mut decoder = {
-            match cached_decoder {
+            let mut cache_guard = self
+                .decoder_cache
+                .write()
+                .map_err(|_| io::Error::other("Failed to acquire decoder cache lock"))?;
+
+            match cache_guard.take() {
                Some(mut cached_decoder) => {
                    if let Err(e) = cached_decoder.reset(self.data_shards, self.parity_shards, shard_len) {
                        warn!("Failed to reset SIMD decoder: {:?}, creating new one", e);
@@ -303,15 +234,10 @@ impl LegacyReedSolomonEncoder {

        drop(result);

-        if self.should_cache_workspace(shard_len) {
-            let mut cache = self
-                .decoder_cache
-                .write()
-                .map_err(|_| io::Error::other("Failed to return decoder to cache"))?;
-            if cache.is_none() {
-                *cache = Some(decoder);
-            }
-        }
+        *self
+            .decoder_cache
+            .write()
+            .map_err(|_| io::Error::other("Failed to return decoder to cache"))? = Some(decoder);

        Ok(())
    }
@@ -469,39 +395,6 @@ fn cached_modern_reed_solomon(data_shards: usize, parity_shards: usize) -> Resul
    Ok(encoder)
 }

-fn cached_legacy_reed_solomon(data_shards: usize, parity_shards: usize) -> io::Result<Arc<LegacyReedSolomonEncoder>> {
-    let cache = LEGACY_REED_SOLOMON_CACHE.get_or_init(|| RwLock::new(HashMap::new()));
-    cached_legacy_reed_solomon_in(cache, data_shards, parity_shards)
-}
-
-fn cached_legacy_reed_solomon_in(
-    cache: &LegacyReedSolomonCache,
-    data_shards: usize,
-    parity_shards: usize,
-) -> io::Result<Arc<LegacyReedSolomonEncoder>> {
-    let key = (data_shards, parity_shards);
-    if let Some(encoder) = cache
-        .read()
-        .unwrap_or_else(|poisoned| poisoned.into_inner())
-        .get(&key)
-        .cloned()
-    {
-        return Ok(encoder);
-    }
-
-    let mut cache = cache.write().unwrap_or_else(|poisoned| poisoned.into_inner());
-    if let Some(existing) = cache.get(&key) {
-        return Ok(Arc::clone(existing));
-    }
-    if cache.len() < LEGACY_REED_SOLOMON_CACHE_MAX_ENTRIES {
-        let encoder = Arc::new(LegacyReedSolomonEncoder::with_workspace_cache(data_shards, parity_shards, true)?);
-        cache.insert(key, Arc::clone(&encoder));
-        return Ok(encoder);
-    }
-    drop(cache);
-    Ok(Arc::new(LegacyReedSolomonEncoder::new(data_shards, parity_shards)?))
-}
-
 fn encode_parity_shards<F>(shards: &mut [Option<Vec<u8>>], data_shards: usize, parity_shards: usize, encode: F) -> io::Result<()>
 where
    F: FnOnce(SmallVec<[&mut [u8]; 16]>) -> io::Result<()>,
@@ -618,7 +511,7 @@ pub struct Erasure {
    pub data_shards: usize,
    pub parity_shards: usize,
    encoder: Option<ReedSolomonEncoder>,
-    legacy_encoder: Option<Arc<LegacyReedSolomonEncoder>>,
+    legacy_encoder: Option<LegacyReedSolomonEncoder>,
    pub block_size: usize,
    uses_legacy: bool,
    _id: Uuid,
@@ -754,7 +647,7 @@ impl Erasure {

        let legacy_encoder = if uses_legacy && parity_shards > 0 {
            Some(
-                cached_legacy_reed_solomon(data_shards, parity_shards)
+                LegacyReedSolomonEncoder::new(data_shards, parity_shards)
                    .map_err(|source| ErasureConstructionError::LegacyEncoder { source })?,
            )
        } else {
@@ -782,48 +675,106 @@ impl Erasure {
    #[tracing::instrument(level = "debug", skip_all, fields(data_len=data.len()))]
    #[hotpath::measure(impl_type = "Erasure")]
    pub fn encode_data(&self, data: &[u8]) -> io::Result<Vec<Bytes>> {
-        self.encode_data_block_inner(data)
-            .map(|block| block.into_shards(self.total_shard_count()))
-    }
+        let shard_size_fn = if self.uses_legacy {
+            calc_shard_size_legacy
+        } else {
+            calc_shard_size
+        };
+        let per_shard_size = shard_size_fn(data.len(), self.data_shards);
+        if per_shard_size == 0 {
+            return Ok(vec![Bytes::new(); self.total_shard_count()]);
+        }
+        let need_total_size = per_shard_size * self.total_shard_count();

-    #[tracing::instrument(level = "debug", skip_all, fields(data_len=data.len()))]
-    #[hotpath::measure(label = "Erasure::encode_data", impl_type = "Erasure")]
-    pub(crate) fn encode_data_block(&self, data: &[u8]) -> io::Result<EncodedBlock> {
-        self.encode_data_block_inner(data)
-    }
-
-    fn encode_data_block_inner(&self, data: &[u8]) -> io::Result<EncodedBlock> {
-        let mut data_buffer = BytesMut::with_capacity(self.encoded_capacity_for_data_len(data.len()));
+        let mut data_buffer = BytesMut::with_capacity(need_total_size);
        data_buffer.extend_from_slice(data);
-        self.encode_buffer(data_buffer, data.len())
+        data_buffer.resize(need_total_size, 0u8);
+
+        {
+            let data_slices: SmallVec<[&mut [u8]; 16]> = data_buffer.chunks_exact_mut(per_shard_size).collect();
+
+            if self.parity_shards > 0 {
+                if self.uses_legacy {
+                    if let Some(encoder) = self.legacy_encoder.as_ref() {
+                        encoder.encode(data_slices)?;
+                    } else {
+                        warn!("parity_shards > 0, uses_legacy but legacy_encoder is None");
+                    }
+                } else if let Some(encoder) = self.encoder.as_ref() {
+                    encoder.encode(data_slices)?;
+                } else {
+                    warn!("parity_shards > 0, but encoder is None");
+                }
+            }
+        }
+
+        // Zero-copy split, all shards reference data_buffer
+        let mut data_buffer = data_buffer.freeze();
+        let mut shards = Vec::with_capacity(self.total_shard_count());
+        for _ in 0..self.total_shard_count() {
+            let shard = data_buffer.split_to(per_shard_size);
+            shards.push(shard);
+        }
+
+        Ok(shards)
    }

    /// Encode owned data, avoiding a copy when the caller already has a heap buffer.
    /// Falls back to copying into a new buffer if zero-copy conversion fails.
    #[hotpath::measure(impl_type = "Erasure")]
    pub fn encode_data_owned(&self, data: Vec<u8>) -> io::Result<Vec<Bytes>> {
-        self.encode_data_owned_block_inner(data)
-            .map(|block| block.into_shards(self.total_shard_count()))
-    }
+        let shard_size_fn = if self.uses_legacy {
+            calc_shard_size_legacy
+        } else {
+            calc_shard_size
+        };
+        let per_shard_size = shard_size_fn(data.len(), self.data_shards);
+        if per_shard_size == 0 {
+            return Ok(vec![Bytes::new(); self.total_shard_count()]);
+        }
+        let need_total_size = per_shard_size * self.total_shard_count();

-    #[hotpath::measure(label = "Erasure::encode_data_owned", impl_type = "Erasure")]
-    pub(crate) fn encode_data_owned_block(&self, data: Vec<u8>) -> io::Result<EncodedBlock> {
-        self.encode_data_owned_block_inner(data)
-    }
-
-    fn encode_data_owned_block_inner(&self, data: Vec<u8>) -> io::Result<EncodedBlock> {
-        let data_len = data.len();
        // Try zero-copy: Vec<u8> -> Bytes -> BytesMut (succeeds when refcount == 1)
-        let data_buffer = match Bytes::from(data).try_into_mut() {
-            Ok(data_buffer) => data_buffer,
+        let mut data_buffer = match Bytes::from(data).try_into_mut() {
+            Ok(mut bm) => {
+                bm.resize(need_total_size, 0u8);
+                bm
+            }
            Err(b) => {
                // Rare path: refcount != 1, fall back to copy
-                let mut data_buffer = BytesMut::with_capacity(self.encoded_capacity_for_data_len(data_len));
-                data_buffer.extend_from_slice(&b);
-                data_buffer
+                let mut bm = BytesMut::with_capacity(need_total_size);
+                bm.extend_from_slice(&b);
+                bm.resize(need_total_size, 0u8);
+                bm
            }
        };
-        self.encode_buffer(data_buffer, data_len)
+
+        {
+            let data_slices: SmallVec<[&mut [u8]; 16]> = data_buffer.chunks_exact_mut(per_shard_size).collect();
+
+            if self.parity_shards > 0 {
+                if self.uses_legacy {
+                    if let Some(encoder) = self.legacy_encoder.as_ref() {
+                        encoder.encode(data_slices)?;
+                    } else {
+                        warn!("parity_shards > 0, uses_legacy but legacy_encoder is None");
+                    }
+                } else if let Some(encoder) = self.encoder.as_ref() {
+                    encoder.encode(data_slices)?;
+                } else {
+                    warn!("parity_shards > 0, but encoder is None");
+                }
+            }
+        }
+
+        let mut data_buffer = data_buffer.freeze();
+        let mut shards = Vec::with_capacity(self.total_shard_count());
+        for _ in 0..self.total_shard_count() {
+            let shard = data_buffer.split_to(per_shard_size);
+            shards.push(shard);
+        }
+
+        Ok(shards)
    }

    /// Encode data from an owned `BytesMut` buffer, avoiding the initial copy
@@ -835,17 +786,7 @@ impl Erasure {
    /// `data_len <= block_size` — both shard-size formulas are monotone in
    /// `data_len` — so this function never reallocates the buffer.
    #[hotpath::measure(impl_type = "Erasure")]
-    pub fn encode_data_bytes_mut(&self, data_buffer: BytesMut, data_len: usize) -> io::Result<Vec<Bytes>> {
-        self.encode_buffer(data_buffer, data_len)
-            .map(|block| block.into_shards(self.total_shard_count()))
-    }
-
-    #[hotpath::measure(label = "Erasure::encode_data_bytes_mut", impl_type = "Erasure")]
-    pub(crate) fn encode_data_bytes_mut_block(&self, data_buffer: BytesMut, data_len: usize) -> io::Result<EncodedBlock> {
-        self.encode_buffer(data_buffer, data_len)
-    }
-
-    fn encode_buffer(&self, mut data_buffer: BytesMut, data_len: usize) -> io::Result<EncodedBlock> {
+    pub fn encode_data_bytes_mut(&self, mut data_buffer: BytesMut, data_len: usize) -> io::Result<Vec<Bytes>> {
        let shard_size_fn = if self.uses_legacy {
            calc_shard_size_legacy
        } else {
@@ -853,7 +794,7 @@ impl Erasure {
        };
        let per_shard_size = shard_size_fn(data_len, self.data_shards);
        if per_shard_size == 0 {
-            return Ok(EncodedBlock::empty());
+            return Ok(vec![Bytes::new(); self.total_shard_count()]);
        }
        let need_total_size = per_shard_size * self.total_shard_count();

@@ -880,10 +821,14 @@ impl Erasure {
            }
        }

-        Ok(EncodedBlock {
-            data: data_buffer.freeze(),
-            shard_size: per_shard_size,
-        })
+        let mut data_buffer = data_buffer.freeze();
+        let mut shards = Vec::with_capacity(self.total_shard_count());
+        for _ in 0..self.total_shard_count() {
+            let shard = data_buffer.split_to(per_shard_size);
+            shards.push(shard);
+        }
+
+        Ok(shards)
    }

    /// Decode and reconstruct missing data shards in-place.
@@ -1472,7 +1417,7 @@ mod tests {
        assert_eq!(cloned.block_size, legacy.block_size);
        assert!(cloned.uses_legacy);

-        let data = b"legacy clone should preserve SIMD codec behavior";
+        let data = b"legacy clone should keep independent SIMD caches";
        let encoded = cloned.encode_data(data).expect("legacy clone should encode");
        let mut shards = optional_shards(&encoded);
        shards[0] = None;
@@ -1480,93 +1425,6 @@ mod tests {
        assert_eq!(recover_data(&shards, cloned.data_shards, data.len()), data);
    }

-    #[test]
-    fn legacy_codecs_share_process_cache_across_erasure_instances() {
-        let first = Erasure::new_with_options(6, 3, 64, true)
-            .legacy_encoder
-            .expect("legacy codec should be initialized");
-        let second = Erasure::new_with_options(6, 3, 128, true)
-            .legacy_encoder
-            .expect("same legacy shard layout should be initialized");
-
-        assert!(Arc::ptr_eq(&first, &second));
-    }
-
-    #[test]
-    fn legacy_workspace_cache_rejects_oversize_buffers_and_isolates_layouts() {
-        let four_plus_two = Erasure::new_with_options(4, 2, 64, true)
-            .legacy_encoder
-            .expect("legacy codec should be initialized");
-        let four_plus_one = Erasure::new_with_options(4, 1, 64, true)
-            .legacy_encoder
-            .expect("distinct parity layout should be initialized");
-        let three_plus_two = Erasure::new_with_options(3, 2, 64, true)
-            .legacy_encoder
-            .expect("distinct data layout should be initialized");
-
-        assert!(!Arc::ptr_eq(&four_plus_two, &four_plus_one));
-        assert!(!Arc::ptr_eq(&four_plus_two, &three_plus_two));
-        assert_eq!(four_plus_two.logical_shard_bytes_upper_bound(64 * 1024), Some(512 * 1024));
-        assert!(four_plus_two.should_cache_workspace(64 * 1024));
-        assert!(!four_plus_two.should_cache_workspace(64 * 1024 + 1));
-
-        let nine_plus_seven =
-            LegacyReedSolomonEncoder::with_workspace_cache(9, 7, true).expect("9+7 legacy codec should construct");
-        assert_eq!(nine_plus_seven.logical_shard_bytes_upper_bound(16 * 1024), Some(512 * 1024));
-        assert!(nine_plus_seven.should_cache_workspace(16 * 1024));
-        assert!(!nine_plus_seven.should_cache_workspace(16 * 1024 + 1));
-
-        let uncached = LegacyReedSolomonEncoder::new(4, 2).expect("uncached legacy codec should construct");
-        assert!(!uncached.should_cache_workspace(64));
-    }
-
-    #[test]
-    fn saturated_legacy_codec_cache_does_not_retain_more_workspaces() {
-        let cache = RwLock::new(HashMap::new());
-        for parity_shards in 1..=LEGACY_REED_SOLOMON_CACHE_MAX_ENTRIES {
-            let cached =
-                cached_legacy_reed_solomon_in(&cache, 32, parity_shards).expect("cacheable legacy codec should construct");
-            assert!(cached.cache_workspaces);
-        }
-
-        let uncached =
-            cached_legacy_reed_solomon_in(&cache, 31, 1).expect("uncached legacy codec should construct after saturation");
-        assert!(!uncached.cache_workspaces);
-        assert_eq!(
-            cache.read().expect("cache lock should remain healthy").len(),
-            LEGACY_REED_SOLOMON_CACHE_MAX_ENTRIES
-        );
-    }
-
-    #[test]
-    fn concurrent_legacy_codecs_preserve_byte_exact_results() {
-        let barrier = Arc::new(std::sync::Barrier::new(2));
-        let payloads = [vec![0x35; 257], vec![0xca; 1025]];
-
-        std::thread::scope(|scope| {
-            let handles = payloads.each_ref().map(|payload| {
-                let barrier = Arc::clone(&barrier);
-                scope.spawn(move || {
-                    let erasure = Erasure::new_with_options(6, 3, 2048, true);
-                    barrier.wait();
-                    let encoded = erasure.encode_data(payload).expect("concurrent legacy encode should succeed");
-                    barrier.wait();
-
-                    let mut shards = optional_shards(&encoded);
-                    shards[0] = None;
-                    erasure
-                        .decode_data(&mut shards)
-                        .expect("concurrent legacy decode should reconstruct the missing shard");
-                    recover_data(&shards, erasure.data_shards, payload.len())
-                })
-            });
-
-            for (handle, payload) in handles.into_iter().zip(payloads.iter()) {
-                assert_eq!(handle.join().expect("concurrent legacy codec worker should not panic"), *payload);
-            }
-        });
-    }
-
    #[test]
    fn legacy_verify_reports_invalid_empty_valid_and_corrupt_parity_sets() {
        let legacy = LegacyReedSolomonEncoder::new(2, 2).expect("legacy encoder should construct");
@@ -1640,16 +1498,10 @@ mod tests {
    fn encode_data_owned_matches_borrowed_path() {
        for uses_legacy in [false, true] {
            let erasure = Erasure::new_with_options(4, 2, 64, uses_legacy);
-            for data in [
-                Vec::new(),
-                vec![0xA5; 1],
-                b"small payload".to_vec(),
-                (0_u8..37).collect(),
-                vec![0xA5; erasure.block_size - 1],
-                vec![0x5A; erasure.block_size],
-            ] {
-                assert_owned_encode_matches_borrowed(&erasure, data);
-            }
+
+            assert_owned_encode_matches_borrowed(&erasure, Vec::new());
+            assert_owned_encode_matches_borrowed(&erasure, b"small payload".to_vec());
+            assert_owned_encode_matches_borrowed(&erasure, (0_u8..37).collect());
        }
    }

@@ -1695,52 +1547,6 @@ mod tests {
        }
    }

-    #[test]
-    fn streaming_encoded_block_uses_one_contiguous_backing_buffer() {
-        for uses_legacy in [false, true] {
-            let erasure = Erasure::new_with_options(8, 8, 64, uses_legacy);
-
-            for data_len in [0, 1, 63, 64] {
-                let data = (0..data_len).map(|i| i as u8).collect::<Vec<_>>();
-                let expected = erasure.encode_data(&data).expect("public encode should succeed");
-                let borrowed = erasure
-                    .encode_data_block(&data)
-                    .expect("borrowed streaming encode should succeed");
-                let owned = erasure
-                    .encode_data_owned_block(data.clone())
-                    .expect("owned streaming encode should succeed");
-                let bytes_mut = erasure
-                    .encode_data_bytes_mut_block(BytesMut::from(&data[..]), data.len())
-                    .expect("BytesMut streaming encode should succeed");
-
-                assert_eq!(borrowed.queued_bytes(), owned.queued_bytes());
-                assert_eq!(borrowed.queued_bytes(), bytes_mut.queued_bytes());
-
-                if data_len == 0 {
-                    assert!(expected.iter().all(Bytes::is_empty));
-                    assert!(borrowed.is_empty());
-                    assert!(owned.is_empty());
-                    assert!(bytes_mut.is_empty());
-                    continue;
-                }
-
-                assert!(borrowed.shards().eq(expected.iter().map(Bytes::as_ref)));
-                assert!(owned.shards().eq(expected.iter().map(Bytes::as_ref)));
-                assert!(bytes_mut.shards().eq(expected.iter().map(Bytes::as_ref)));
-                assert_eq!(borrowed.shards().len(), 16);
-                let first = borrowed.shards().next().expect("encoded block should have shards").as_ptr();
-                for (index, shard) in borrowed.shards().enumerate() {
-                    assert_eq!(shard.as_ptr(), first.wrapping_add(index * shard.len()));
-                }
-            }
-        }
-        assert_eq!(
-            std::mem::size_of::<EncodedBlock>(),
-            std::mem::size_of::<Bytes>() + std::mem::size_of::<usize>(),
-            "queue entries must contain one backing buffer handle, not per-shard handles"
-        );
-    }
-
    /// HP-10 capacity invariant: both shard-size formulas are monotone in `data_len`,
    /// so pre-reserving `shard_size(block_size) * total_shard_count` covers the
    /// `need_total_size` of every block-or-smaller payload and the ingest buffer
@@ -22,13 +22,12 @@ use crate::diagnostics::get::{
 #[cfg(feature = "hotpath")]
 use crate::disk::FileWriter;
 use crate::disk::{self, DiskAPI as _, DiskStore, FileReader, MmapCopyStageMetrics, error::DiskError};
-use crate::erasure::coding::{BitrotReader, BitrotWriterWrapper, CustomWriter, ShardChunkRead};
+use crate::erasure::coding::{BitrotReader, BitrotWriterWrapper, CustomWriter};
 use bytes::Bytes;
 use rustfs_config::{
    DEFAULT_OBJECT_MMAP_READ_ENABLE, DEFAULT_OBJECT_MMAP_READ_MAX_LENGTH, ENV_OBJECT_MMAP_READ_ENABLE,
    ENV_OBJECT_MMAP_READ_MAX_LENGTH, ENV_OBJECT_ZERO_COPY_ENABLE,
 };
-use rustfs_rio::ChunkReaderBox;
 use rustfs_utils::HashAlgorithm;
 use std::future::Future;
 use std::io::{self, Cursor};
@@ -52,25 +51,13 @@ tokio::task_local! {
 /// (rustfs/backlog#1159). Everything else is a stream and keeps the old path.
 pub enum ShardReader {
    InMemory(Cursor<Bytes>),
-    Chunked(ChunkReaderBox),
    Stream(Box<dyn AsyncRead + Send + Sync + Unpin>),
 }

-#[cfg(test)]
-impl ShardReader {
-    pub(crate) fn inline_bytes(&self) -> Option<&Bytes> {
-        match self {
-            Self::InMemory(cursor) => Some(cursor.get_ref()),
-            Self::Chunked(_) | Self::Stream(_) => None,
-        }
-    }
-}
-
 impl AsyncRead for ShardReader {
    fn poll_read(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut tokio::io::ReadBuf<'_>) -> Poll<std::io::Result<()>> {
        match self.get_mut() {
            Self::InMemory(cursor) => Pin::new(cursor).poll_read(cx, buf),
-            Self::Chunked(reader) => Pin::new(&mut **reader).poll_read(cx, buf),
            Self::Stream(reader) => Pin::new(reader).poll_read(cx, buf),
        }
    }
@@ -80,19 +67,7 @@ impl crate::erasure::coding::ShardSource for ShardReader {
    fn try_take_block(&mut self, n: usize) -> Option<Bytes> {
        match self {
            Self::InMemory(cursor) => cursor.try_take_block(n),
-            Self::Chunked(_) | Self::Stream(_) => None,
-        }
-    }
-
-    fn poll_read_chunk(self: Pin<&mut Self>, cx: &mut Context<'_>, max: usize) -> Poll<io::Result<ShardChunkRead>> {
-        let Self::Chunked(reader) = self.get_mut() else {
-            return Poll::Ready(Ok(ShardChunkRead::Unsupported));
-        };
-        match Pin::new(&mut **reader).poll_read_chunk(cx, max) {
-            Poll::Ready(Ok(Some(chunk))) => Poll::Ready(Ok(ShardChunkRead::Chunk(chunk))),
-            Poll::Ready(Ok(None)) => Poll::Ready(Ok(ShardChunkRead::Eof)),
-            Poll::Ready(Err(err)) => Poll::Ready(Err(err)),
-            Poll::Pending => Poll::Pending,
+            Self::Stream(_) => None,
        }
    }
 }
@@ -370,17 +345,6 @@ async fn open_disk_reader(
    let metrics_path = metrics_path.filter(|_| rustfs_io_metrics::get_stage_metrics_enabled());
    let stage_metrics_enabled = metrics_path.is_some();

-    // Preserve HTTP body ownership only on healthy remote reads. Instrumented
-    // and local paths retain their existing AsyncRead wrappers.
-    if use_mmap_read
-        && !disk.is_local()
-        && !stage_metrics_enabled
-        && !cfg!(feature = "hotpath")
-        && let Some(reader) = disk.read_file_stream_chunks(bucket, path, offset, length).await?
-    {
-        return Ok(ShardReader::Chunked(reader));
-    }
-
    // Mmap-copy materializes the whole `offset..offset+length` range as one
    // owned allocation before any byte is served, and GET/heal shard reads
    // request the entire part span in one call. Over-cap reads (e.g. a huge
@@ -656,7 +620,7 @@ pub async fn create_bitrot_reader_from_bytes(
 }

 #[allow(clippy::too_many_arguments)]
-pub(crate) async fn create_bitrot_reader_from_bytes_with_stage_metrics(
+async fn create_bitrot_reader_from_bytes_with_stage_metrics(
    inline_data: Option<Bytes>,
    disk: Option<&DiskStore>,
    bucket: &str,
@@ -816,50 +780,6 @@ pub async fn create_bitrot_writer(
 #[cfg(test)]
 mod tests {
    use super::*;
-    use rustfs_rio::ChunkReader;
-    use std::collections::VecDeque;
-
-    struct TestChunkReader {
-        chunks: VecDeque<Bytes>,
-    }
-
-    impl TestChunkReader {
-        fn new(bytes: Bytes, fragment_sizes: &[usize]) -> Self {
-            let mut chunks = VecDeque::new();
-            let mut offset = 0;
-            for &size in fragment_sizes {
-                let end = (offset + size).min(bytes.len());
-                if offset < end {
-                    chunks.push_back(bytes.slice(offset..end));
-                }
-                offset = end;
-            }
-            if offset < bytes.len() {
-                chunks.push_back(bytes.slice(offset..));
-            }
-            Self { chunks }
-        }
-    }
-
-    impl AsyncRead for TestChunkReader {
-        fn poll_read(self: Pin<&mut Self>, _cx: &mut Context<'_>, _buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
-            Poll::Ready(Err(io::Error::other("test chunk reader must use chunk handoff")))
-        }
-    }
-
-    impl ChunkReader for TestChunkReader {
-        fn poll_read_chunk(mut self: Pin<&mut Self>, _cx: &mut Context<'_>, max: usize) -> Poll<io::Result<Option<Bytes>>> {
-            let Some(mut chunk) = self.chunks.pop_front() else {
-                return Poll::Ready(Ok(None));
-            };
-            let take = chunk.len().min(max);
-            if take < chunk.len() {
-                self.chunks.push_front(chunk.split_off(take));
-            }
-            chunk.truncate(take);
-            Poll::Ready(Ok(Some(chunk)))
-        }
-    }

    #[cfg(feature = "hotpath")]
    use crate::cluster::rpc::RemoteDisk;
@@ -1749,49 +1669,4 @@ mod tests {
        println!("error: {error:?}");
        assert_eq!(error, DiskError::DiskNotFound);
    }
-
-    #[tokio::test]
-    async fn shard_reader_chunked_path_verifies_fragmented_remote_block() {
-        const SHARD_SIZE: usize = 1024;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let data = vec![42u8; SHARD_SIZE];
-        let mut encoded = Vec::new();
-        crate::erasure::coding::BitrotWriter::new(&mut encoded, SHARD_SIZE, algo.clone())
-            .write(&data)
-            .await
-            .expect("test shard should encode");
-
-        let source = TestChunkReader::new(Bytes::from(encoded), &[3, 7, 17, 31]);
-        let mut reader = BitrotReader::new(ShardReader::Chunked(Box::new(source)), SHARD_SIZE, algo, false);
-        let mut output = Vec::with_capacity(SHARD_SIZE);
-        reader
-            .read_appending(&mut output, SHARD_SIZE)
-            .await
-            .expect("fragmented remote shard should verify");
-
-        assert_eq!(output, data);
-    }
-
-    #[tokio::test]
-    async fn shard_reader_chunked_path_handles_more_than_one_poll_budget() {
-        const SHARD_SIZE: usize = 1024;
-        let algo = HashAlgorithm::HighwayHash256S;
-        let data = vec![42u8; SHARD_SIZE];
-        let mut encoded = Vec::new();
-        crate::erasure::coding::BitrotWriter::new(&mut encoded, SHARD_SIZE, algo.clone())
-            .write(&data)
-            .await
-            .expect("test shard should encode");
-
-        let fragment_sizes = vec![1; encoded.len()];
-        let source = TestChunkReader::new(Bytes::from(encoded), &fragment_sizes);
-        let mut reader = BitrotReader::new(ShardReader::Chunked(Box::new(source)), SHARD_SIZE, algo, false);
-        let mut output = Vec::with_capacity(SHARD_SIZE);
-        reader
-            .read_appending(&mut output, SHARD_SIZE)
-            .await
-            .expect("fragmented remote shard should verify after multiple polls");
-
-        assert_eq!(output, data);
-    }
 }
@@ -21,8 +21,7 @@ use tracing::debug;

 /// Supported set sizes this is used to find the optimal
 /// single set size.
-pub(crate) const MAX_ERASURE_SET_DRIVE_COUNT: usize = 16;
-const SET_SIZES: [usize; 15] = [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, MAX_ERASURE_SET_DRIVE_COUNT];
+const SET_SIZES: [usize; 15] = [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
 const ENV_RUSTFS_ERASURE_SET_DRIVE_COUNT: &str = "RUSTFS_ERASURE_SET_DRIVE_COUNT";

 #[derive(Deserialize, Debug, Default)]
@@ -328,7 +327,7 @@ fn possible_set_counts(set_size: usize) -> Vec<usize> {

 /// checks whether given count is a valid set size for erasure coding.
 fn is_valid_set_size(count: usize) -> bool {
-    count >= SET_SIZES[0] && count <= MAX_ERASURE_SET_DRIVE_COUNT
+    count >= SET_SIZES[0] && count <= SET_SIZES[SET_SIZES.len() - 1]
 }

 /// Final set size with all the symmetry accounted for.
@@ -15,7 +15,6 @@
 use super::*;

 use crate::io_support::rio::Index;
-use std::mem::MaybeUninit;

 #[cfg(feature = "rio-v2")]
 const DARE_PAYLOAD_SIZE: i64 = 64 * 1024;
@@ -923,7 +922,7 @@ struct SkipReader<R> {
    inner: R,
    bytes_to_skip: usize,
    bytes_skipped: usize,
-    scratch: Box<[MaybeUninit<u8>]>,
+    scratch: Vec<u8>,
 }

 impl<R: AsyncRead + Unpin + Send + Sync> SkipReader<R> {
@@ -932,7 +931,7 @@ impl<R: AsyncRead + Unpin + Send + Sync> SkipReader<R> {
            inner,
            bytes_to_skip,
            bytes_skipped: 0,
-            scratch: Box::<[u8]>::new_uninit_slice(8192),
+            scratch: vec![0u8; 8192],
        }
    }
 }
@@ -944,7 +943,7 @@ impl<R: AsyncRead + Unpin + Send + Sync> AsyncRead for SkipReader<R> {
        while this.bytes_skipped < this.bytes_to_skip {
            let remaining = this.bytes_to_skip - this.bytes_skipped;
            let scratch_len = remaining.min(this.scratch.len());
-            let mut scratch_buf = ReadBuf::uninit(&mut this.scratch[..scratch_len]);
+            let mut scratch_buf = ReadBuf::new(&mut this.scratch[..scratch_len]);
            match Pin::new(&mut this.inner).poll_read(cx, &mut scratch_buf) {
                Poll::Pending => return Poll::Pending,
                Poll::Ready(Err(err)) => return Poll::Ready(Err(err)),
@@ -975,7 +974,7 @@ pub struct RangedDecompressReader<R: AsyncRead + Unpin + Send + Sync + 'static>
    target_length: usize,
    current_offset: usize,
    bytes_returned: usize,
-    scratch: Box<[MaybeUninit<u8>]>,
+    scratch: Vec<u8>,
    drain_on_done: bool,
    drain_task: Option<tokio::task::JoinHandle<()>>,
 }
@@ -1013,7 +1012,7 @@ impl<R: AsyncRead + Unpin + Send + Sync + 'static> RangedDecompressReader<R> {
            target_length: actual_length,
            current_offset: 0,
            bytes_returned: 0,
-            scratch: Box::<[u8]>::new_uninit_slice(8192),
+            scratch: vec![0u8; 8192],
            drain_on_done,
            drain_task: None,
        })
@@ -1063,7 +1062,7 @@ impl<R: AsyncRead + Unpin + Send + Sync + 'static> AsyncRead for RangedDecompres
            }

            let scratch_len = std::cmp::min(this.scratch.len(), std::cmp::max(buf_capacity, 1));
-            let mut temp_read_buf = ReadBuf::uninit(&mut this.scratch[..scratch_len]);
+            let mut temp_read_buf = ReadBuf::new(&mut this.scratch[..scratch_len]);

            let Some(inner) = this.inner.as_mut() else {
                return Poll::Ready(Ok(()));
@@ -1115,8 +1114,7 @@ impl<R: AsyncRead + Unpin + Send + Sync + 'static> AsyncRead for RangedDecompres
                            );

                            if bytes_to_return > 0 {
-                                let data_slice =
-                                    &temp_read_buf.filled()[data_start_in_buffer..data_start_in_buffer + bytes_to_return];
+                                let data_slice = &this.scratch[data_start_in_buffer..data_start_in_buffer + bytes_to_return];
                                buf.put_slice(data_slice);
                                this.bytes_returned += bytes_to_return;

@@ -1135,7 +1133,7 @@ impl<R: AsyncRead + Unpin + Send + Sync + 'static> AsyncRead for RangedDecompres
                            std::cmp::min(n, std::cmp::min(buf.remaining(), this.target_length - this.bytes_returned));

                        if bytes_to_return > 0 {
-                            buf.put_slice(&temp_read_buf.filled()[..bytes_to_return]);
+                            buf.put_slice(&this.scratch[..bytes_to_return]);
                            this.bytes_returned += bytes_to_return;

                            tracing::trace!("Returned {} bytes at offset {}", bytes_to_return, old_offset);
@@ -1265,43 +1263,6 @@ mod tests {
    use temp_env::async_with_vars;
    use tokio::io::AsyncReadExt;

-    #[derive(Debug)]
-    struct PendingPartialReader {
-        data: &'static [u8],
-        position: usize,
-        pending: bool,
-    }
-
-    impl PendingPartialReader {
-        fn new(data: &'static [u8]) -> Self {
-            Self {
-                data,
-                position: 0,
-                pending: true,
-            }
-        }
-    }
-
-    impl AsyncRead for PendingPartialReader {
-        fn poll_read(mut self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>) -> Poll<std::io::Result<()>> {
-            if self.pending {
-                self.pending = false;
-                cx.waker().wake_by_ref();
-                return Poll::Pending;
-            }
-            if self.position == self.data.len() {
-                return Poll::Ready(Ok(()));
-            }
-
-            let length = buf.remaining().min(3).min(self.data.len() - self.position);
-            let end = self.position + length;
-            buf.put_slice(&self.data[self.position..end]);
-            self.position = end;
-            self.pending = true;
-            Poll::Ready(Ok(()))
-        }
-    }
-
    const TEST_DIRECT_KEY_HEADER: &str = "x-rustfs-test-direct-key";
    const TEST_OBJECT_KEY_HEADER: &str = "x-rustfs-test-object-key";
    const TEST_NONCE_HEADER: &str = "x-rustfs-test-nonce";
@@ -1439,36 +1400,6 @@ mod tests {
        assert_eq!(result, b"World");
    }

-    #[tokio::test]
-    async fn uninitialized_scratch_preserves_partial_pending_and_eof_reads() {
-        let mut skipped = SkipReader::new(PendingPartialReader::new(b"0123456789abcdef"), 5);
-        let mut skipped_output = Vec::new();
-        skipped
-            .read_to_end(&mut skipped_output)
-            .await
-            .expect("skip reader should survive partial pending reads through EOF");
-        assert_eq!(skipped_output, b"56789abcdef");
-
-        let mut ranged = RangedDecompressReader::new(PendingPartialReader::new(b"0123456789abcdef"), 5, 7, 16)
-            .expect("valid range should construct");
-        let mut ranged_output = Vec::new();
-        ranged
-            .read_to_end(&mut ranged_output)
-            .await
-            .expect("range reader should survive partial pending reads through EOF");
-        assert_eq!(ranged_output, b"56789ab");
-    }
-
-    #[tokio::test]
-    async fn uninitialized_skip_scratch_reports_early_eof() {
-        let mut reader = SkipReader::new(PendingPartialReader::new(b"short"), 6);
-        let error = reader
-            .read_to_end(&mut Vec::new())
-            .await
-            .expect_err("EOF before the skip boundary must remain visible");
-        assert_eq!(error.kind(), std::io::ErrorKind::UnexpectedEof);
-    }
-
    #[tokio::test]
    async fn test_ranged_decompress_reader_from_start() {
        let original_data = b"Hello, World! This is a test.";
@@ -260,9 +260,6 @@ pub struct ObjectOptions {

    pub data_movement: bool,
    pub raw_data_movement_read: bool,
-    /// Materialize the data-movement per-part checksum sidecar for APIs that
-    /// return part checksums. Ordinary object reads leave it encoded.
-    pub include_part_checksums: bool,
    pub src_pool_idx: usize,
    pub user_defined: HashMap<String, String>,
    pub preserve_etag: Option<String>,
@@ -164,9 +164,6 @@ pub(crate) async fn local_node_name() -> String {
 }

 pub(crate) async fn set_local_node_name(node_name: String) {
-    // Also stamp the internode-metrics server label: io-metrics is a leaf
-    // crate and no longer resolves node identity itself (backlog#1834).
-    rustfs_io_metrics::internode_metrics::set_internode_server_label(node_name.as_str());
    rustfs_common::set_global_local_node_name(&node_name).await;
 }

@@ -16,7 +16,7 @@ use super::meta::{
    clone_arc_by_index, ensure_valid_rebalance_pool_index, invalid_rebalance_pool_index_error,
    rebalance_metadata_not_initialized_error, should_ignore_rebalance_data_usage_cache,
 };
-use super::migration::{RebalanceMigrationBackend, migrate_entry_version};
+use super::migration::migrate_entry_version;
 use super::worker::{
    RebalanceEntryCleanupResult, RebalanceEntryTask, load_rebalance_bucket_configs, rebalance_max_attempts,
    resolve_rebalance_bucket_error, resolve_rebalance_entry_cleanup_delete_result, resolve_rebalance_file_info_versions_result,
@@ -144,11 +144,6 @@ impl ECStore {
            return Ok(RebalanceEntryOutcome::Completed);
        }

-        let bucket_incarnation_fence = match bucket_configs.bucket_incarnation_id {
-            Some(expected) => Some(self.acquire_bucket_incarnation_fence(&bucket, expected).await?),
-            None => None,
-        };
-
        let mut fivs =
            resolve_rebalance_file_info_versions_result(entry.file_info_versions(&bucket), bucket.as_str(), entry.name.as_str())?;

@@ -208,14 +203,9 @@ impl ECStore {
            }

            let version_id = version.version_id.map(|v| v.to_string());
-            let expected_bucket_incarnation_id = bucket_configs.bucket_incarnation_id;
            let mut transfer = |src_pool_idx: usize, bucket: String, rd: GetObjectReader| {
                let store = self.clone();
-                async move {
-                    store
-                        .rebalance_object(src_pool_idx, bucket, rd, expected_bucket_incarnation_id)
-                        .await
-                }
+                async move { store.rebalance_object(src_pool_idx, bucket, rd).await }
            };
            // Route delete-marker migration through the store layer so it lands on the
            // cross-pool target (excluding the source pool), not back onto the source set.
@@ -224,12 +214,11 @@ impl ECStore {
                async move { store.delete_object(&bucket, &object, opts).await }
            };
            let result = migrate_entry_version(
-                &RebalanceMigrationBackend::new(set.as_ref(), self.as_ref()),
+                set.as_ref(),
                bucket.clone(),
                pool_index,
                version,
                version_id.clone(),
-                expected_bucket_incarnation_id,
                rebalance_max_attempts(),
                should_ignore_rebalance_data_usage_cache(bucket.as_str()),
                &mut transfer,
@@ -314,9 +303,6 @@ impl ECStore {
        }

        if should_cleanup_rebalance_source_entry(rebalanced, fivs.versions.len(), expired) {
-            if bucket_incarnation_fence.as_ref().is_some_and(|guard| guard.is_lock_lost()) {
-                return Err(Error::other("rebalance bucket incarnation fence was lost before source cleanup"));
-            }
            let cleanup_result = self
                .finish_rebalance_entry_after_cleanup(
                    pool_index,
@@ -329,12 +315,6 @@ impl ECStore {
                        entry.name.as_str(),
                        &fivs,
                        &cleanup_preflight_allowed_missing,
-                        data_movement::SourceCleanupBucketFence {
-                            expected_incarnation_id: bucket_configs.bucket_incarnation_id,
-                            lifecycle_guard: bucket_incarnation_fence
-                                .as_ref()
-                                .and_then(|guard| guard.namespace_lock_guard()),
-                        },
                        "rebalance",
                    ),
                )
@@ -409,14 +389,8 @@ impl ECStore {
    }

    #[tracing::instrument(skip(self, rd))]
-    async fn rebalance_object(
-        self: Arc<Self>,
-        pool_idx: usize,
-        bucket: String,
-        rd: GetObjectReader,
-        expected_bucket_incarnation_id: Option<uuid::Uuid>,
-    ) -> Result<()> {
-        data_movement::migrate_object(self, pool_idx, bucket, rd, expected_bucket_incarnation_id, "rebalance_object").await
+    async fn rebalance_object(self: Arc<Self>, pool_idx: usize, bucket: String, rd: GetObjectReader) -> Result<()> {
+        data_movement::migrate_object(self, pool_idx, bucket, rd, "rebalance_object").await
    }

    async fn update_rebalance_last_error(&self, pool_idx: usize, message: String) -> Result<()> {
@@ -5,7 +5,6 @@ use crate::error::{Error, Result, is_err_object_not_found, is_err_version_not_fo
 use crate::object_api::{GetObjectReader, ObjectInfo, ObjectOptions};
 use crate::set_disk::SetDisks;
 use crate::storage_api_contracts::{object::ObjectIO, range::HTTPRangeSpec};
-use crate::store::ECStore;
 use http::HeaderMap;
 use rustfs_filemeta::FileInfo;
 use rustfs_utils::path::encode_dir_object;
@@ -22,23 +21,15 @@ pub(crate) struct MigrationVersionResult {
    pub error: Option<Error>,
 }

-pub(super) fn rebalance_delete_marker_opts(
-    version: &FileInfo,
-    version_id: Option<String>,
-    src_pool_idx: usize,
-    expected_bucket_incarnation_id: Option<uuid::Uuid>,
-) -> ObjectOptions {
-    let version_suspended = version.version_id.is_none() && version_id.is_none();
+pub(super) fn rebalance_delete_marker_opts(version: &FileInfo, version_id: Option<String>, src_pool_idx: usize) -> ObjectOptions {
    ObjectOptions {
-        versioned: !version_suspended,
-        version_suspended,
-        version_id: version_id.or_else(|| version_suspended.then(|| uuid::Uuid::nil().to_string())),
+        versioned: true,
+        version_id,
        mod_time: version.mod_time,
        src_pool_idx,
        data_movement: true,
        delete_marker: true,
        skip_decommissioned: true,
-        expected_bucket_incarnation_id,
        delete_replication: version
            .replication_state_internal
            .as_ref()
@@ -47,12 +38,7 @@ pub(super) fn rebalance_delete_marker_opts(
    }
 }

-fn rebalance_remote_tiered_opts(
-    version: &FileInfo,
-    version_id: Option<String>,
-    src_pool_idx: usize,
-    expected_bucket_incarnation_id: Option<uuid::Uuid>,
-) -> ObjectOptions {
+fn rebalance_remote_tiered_opts(version: &FileInfo, version_id: Option<String>, src_pool_idx: usize) -> ObjectOptions {
    ObjectOptions {
        versioned: version_id.is_some(),
        version_id,
@@ -60,21 +46,6 @@ fn rebalance_remote_tiered_opts(
        user_defined: version.metadata.clone(),
        src_pool_idx,
        data_movement: true,
-        include_part_checksums: true,
-        http_preconditions: Some(crate::data_movement::data_movement_target_precondition()),
-        expected_bucket_incarnation_id,
-        ..Default::default()
-    }
-}
-
-pub(super) fn rebalance_object_migration_read_opts(version_id: Option<String>) -> ObjectOptions {
-    ObjectOptions {
-        version_id,
-        no_lock: true,
-        data_movement: true,
-        raw_data_movement_read: true,
-        skip_decommissioned: true,
-        skip_rebalancing: true,
        ..Default::default()
    }
 }
@@ -99,19 +70,8 @@ pub(crate) trait MigrationBackend: Send + Sync {
    ) -> Result<()>;
 }

-pub(crate) struct RebalanceMigrationBackend<'a> {
-    source: &'a SetDisks,
-    store: &'a ECStore,
-}
-
-impl<'a> RebalanceMigrationBackend<'a> {
-    pub(crate) fn new(source: &'a SetDisks, store: &'a ECStore) -> Self {
-        Self { source, store }
-    }
-}
-
 #[async_trait::async_trait]
-impl MigrationBackend for RebalanceMigrationBackend<'_> {
+impl MigrationBackend for SetDisks {
    async fn get_object_reader_for_migration(
        &self,
        bucket: &str,
@@ -120,7 +80,7 @@ impl MigrationBackend for RebalanceMigrationBackend<'_> {
        h: HeaderMap,
        opts: &ObjectOptions,
    ) -> Result<GetObjectReader> {
-        self.source.get_object_reader(bucket, object, range, h, opts).await
+        self.get_object_reader(bucket, object, range, h, opts).await
    }

    async fn move_remote_version_for_migration(
@@ -130,7 +90,7 @@ impl MigrationBackend for RebalanceMigrationBackend<'_> {
        fi: &FileInfo,
        opts: &ObjectOptions,
    ) -> Result<()> {
-        self.store.decommission_tiered_object(bucket, object, fi, opts).await
+        self.decommission_tiered_object(bucket, object, fi, opts).await
    }
 }

@@ -141,7 +101,6 @@ pub(crate) async fn migrate_entry_version<Backend, F, Fut, D, DFut>(
    pool_index: usize,
    version: &FileInfo,
    version_id: Option<String>,
-    expected_bucket_incarnation_id: Option<uuid::Uuid>,
    max_attempts: usize,
    ignore_data_usage_cache: bool,
    transfer: F,
@@ -154,13 +113,12 @@ where
    D: FnMut(String, String, ObjectOptions) -> DFut + Send,
    DFut: Future<Output = Result<ObjectInfo>> + Send,
 {
-    migrate_entry_version_with_retry_wait_and_incarnation(
+    migrate_entry_version_with_retry_wait(
        set,
        bucket,
        pool_index,
        version,
        version_id,
-        expected_bucket_incarnation_id,
        max_attempts,
        ignore_data_usage_cache,
        transfer,
@@ -179,45 +137,6 @@ pub(super) async fn migrate_entry_version_with_retry_wait<Backend, F, Fut, D, DF
    version_id: Option<String>,
    max_attempts: usize,
    ignore_data_usage_cache: bool,
-    transfer: F,
-    delete_marker: D,
-    wait_retry: W,
-) -> MigrationVersionResult
-where
-    Backend: MigrationBackend + ?Sized,
-    F: FnMut(usize, String, GetObjectReader) -> Fut + Send,
-    Fut: Future<Output = Result<()>> + Send,
-    D: FnMut(String, String, ObjectOptions) -> DFut + Send,
-    DFut: Future<Output = Result<ObjectInfo>> + Send,
-    W: FnMut(Duration) -> WFut + Send,
-    WFut: Future<Output = ()> + Send,
-{
-    migrate_entry_version_with_retry_wait_and_incarnation(
-        set,
-        bucket,
-        pool_index,
-        version,
-        version_id,
-        None,
-        max_attempts,
-        ignore_data_usage_cache,
-        transfer,
-        delete_marker,
-        wait_retry,
-    )
-    .await
-}
-
-#[allow(clippy::too_many_arguments)]
-async fn migrate_entry_version_with_retry_wait_and_incarnation<Backend, F, Fut, D, DFut, W, WFut>(
-    set: &Backend,
-    bucket: String,
-    pool_index: usize,
-    version: &FileInfo,
-    version_id: Option<String>,
-    expected_bucket_incarnation_id: Option<uuid::Uuid>,
-    max_attempts: usize,
-    ignore_data_usage_cache: bool,
    mut transfer: F,
    mut delete_marker: D,
    mut wait_retry: W,
@@ -250,7 +169,7 @@ where
                &bucket,
                &version.name,
                version,
-                &rebalance_remote_tiered_opts(version, version_id, pool_index, expected_bucket_incarnation_id),
+                &rebalance_remote_tiered_opts(version, version_id, pool_index),
            )
            .await
        {
@@ -293,7 +212,7 @@ where
        if let Err(err) = delete_marker(
            bucket.clone(),
            version.name.clone(),
-            rebalance_delete_marker_opts(version, version_id, pool_index, expected_bucket_incarnation_id),
+            rebalance_delete_marker_opts(version, version_id, pool_index),
        )
        .await
        {
@@ -336,7 +255,11 @@ where
                &encode_dir_object(&version.name),
                None,
                HeaderMap::new(),
-                &rebalance_object_migration_read_opts(version_id.clone()),
+                &ObjectOptions {
+                    version_id: version_id.clone(),
+                    no_lock: true,
+                    ..Default::default()
+                },
            )
            .await
        {
@@ -113,8 +113,6 @@ struct LegacyRebalanceMeta {
 struct MigrationBackendSpy {
    get_object_reader: Mutex<Option<core::result::Result<GetObjectReader, Error>>>,
    move_remote: Mutex<Option<core::result::Result<(), Error>>>,
-    get_opts: Mutex<Vec<ObjectOptions>>,
-    move_remote_opts: Mutex<Vec<ObjectOptions>>,
    get_calls: AtomicUsize,
    move_remote_calls: AtomicUsize,
 }
@@ -127,8 +125,6 @@ impl MigrationBackendSpy {
        Self {
            get_object_reader: Mutex::new(get_object_reader),
            move_remote: Mutex::new(move_remote),
-            get_opts: Mutex::new(Vec::new()),
-            move_remote_opts: Mutex::new(Vec::new()),
            get_calls: AtomicUsize::new(0),
            move_remote_calls: AtomicUsize::new(0),
        }
@@ -142,24 +138,6 @@ impl MigrationBackendSpy {
        self.move_remote_calls.load(Ordering::SeqCst)
    }

-    fn last_get_opts(&self) -> ObjectOptions {
-        self.get_opts
-            .lock()
-            .unwrap()
-            .last()
-            .cloned()
-            .expect("reader opts should be captured")
-    }
-
-    fn last_move_remote_opts(&self) -> ObjectOptions {
-        self.move_remote_opts
-            .lock()
-            .unwrap()
-            .last()
-            .cloned()
-            .expect("remote opts should be captured")
-    }
-
    fn make_reader() -> GetObjectReader {
        GetObjectReader {
            stream: Box::new(Cursor::new(vec![0_u8; 3])),
@@ -178,10 +156,9 @@ impl MigrationBackend for MigrationBackendSpy {
        _object: &str,
        _range: Option<HTTPRangeSpec>,
        _h: http::HeaderMap,
-        opts: &ObjectOptions,
+        _opts: &ObjectOptions,
    ) -> Result<GetObjectReader> {
        self.get_calls.fetch_add(1, Ordering::SeqCst);
-        self.get_opts.lock().unwrap().push(opts.clone());
        if let Some(result) = self.get_object_reader.lock().unwrap().take() {
            return result;
        }
@@ -194,10 +171,9 @@ impl MigrationBackend for MigrationBackendSpy {
        _bucket: &str,
        _object: &str,
        _fi: &FileInfo,
-        opts: &ObjectOptions,
+        _opts: &ObjectOptions,
    ) -> Result<()> {
        self.move_remote_calls.fetch_add(1, Ordering::SeqCst);
-        self.move_remote_opts.lock().unwrap().push(opts.clone());
        if let Some(result) = self.move_remote.lock().unwrap().take() {
            return result;
        }
@@ -241,8 +217,7 @@ fn test_rebalance_delete_marker_opts_preserves_replication_state() {
        ..version_deleted()
    };

-    let incarnation = uuid::Uuid::new_v4();
-    let opts = rebalance_delete_marker_opts(&version, Some("version-id".to_string()), 7, Some(incarnation));
+    let opts = rebalance_delete_marker_opts(&version, Some("version-id".to_string()), 7);
    let replication = opts.delete_replication.expect("replication state should be preserved");

    assert!(opts.versioned);
@@ -252,22 +227,11 @@ fn test_rebalance_delete_marker_opts_preserves_replication_state() {
    assert_eq!(opts.src_pool_idx, 7);
    assert_eq!(opts.version_id.as_deref(), Some("version-id"));
    assert_eq!(opts.mod_time, Some(mod_time));
-    assert_eq!(opts.expected_bucket_incarnation_id, Some(incarnation));
    assert_eq!(replication.replica_status, ReplicationStatusType::Replica);
    assert!(replication.delete_marker);
    assert_eq!(replication.replicate_decision_str, "existing");
 }

-#[test]
-fn test_rebalance_delete_marker_opts_preserves_suspended_null_version() {
-    let version = version_deleted();
-    let opts = rebalance_delete_marker_opts(&version, None, 7, None);
-
-    assert!(!opts.versioned);
-    assert!(opts.version_suspended);
-    assert_eq!(opts.version_id.as_deref(), Some(uuid::Uuid::nil().to_string().as_str()));
-}
-
 #[tokio::test]
 async fn test_migrate_entry_version_remote_version_is_moved_without_transfer() {
    let backend = MigrationBackendSpy::new(None, Some(Ok(())));
@@ -284,14 +248,12 @@ async fn test_migrate_entry_version_remote_version_is_moved_without_transfer() {
        }
    };

-    let incarnation = uuid::Uuid::new_v4();
    let result = migrate_entry_version(
        &backend,
        "bucket".to_string(),
        0,
        &version,
        version.version_id.map(|v| v.to_string()),
-        Some(incarnation),
        3,
        false,
        &mut transfer,
@@ -307,10 +269,6 @@ async fn test_migrate_entry_version_remote_version_is_moved_without_transfer() {
    assert_eq!(transfer_count.load(Ordering::SeqCst), 0);
    assert_eq!(backend.move_remote_calls(), 1);
    assert_eq!(backend.get_calls(), 0);
-    let remote_opts = backend.last_move_remote_opts();
-    assert!(remote_opts.include_part_checksums);
-    assert!(remote_opts.http_preconditions.is_some());
-    assert_eq!(remote_opts.expected_bucket_incarnation_id, Some(incarnation));
 }

 #[tokio::test]
@@ -336,7 +294,6 @@ async fn test_migrate_entry_version_remote_not_found_is_cleanup_ignored() {
        0,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -373,7 +330,6 @@ async fn test_migrate_entry_version_remote_overwrite_is_not_ignored() {
        0,
        &version,
        Some("vid-1".to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -412,7 +368,6 @@ async fn test_migrate_entry_version_remote_failure_is_reported() {
        0,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -455,7 +410,6 @@ async fn test_migrate_entry_version_deleted_version_routes_delete_through_store_
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -495,7 +449,6 @@ async fn test_migrate_entry_version_deleted_version_not_found_is_ignored() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -538,7 +491,6 @@ async fn test_migrate_entry_version_deleted_version_overwrite_is_not_ignored() {
        1,
        &version,
        Some("vid-1".to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -568,7 +520,6 @@ async fn test_migrate_entry_version_reader_not_found_is_ignored() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -696,7 +647,6 @@ async fn test_migrate_entry_version_reader_fails_after_retries() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -735,7 +685,6 @@ async fn test_migrate_entry_version_zero_max_attempts_still_attempts_once() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        0,
        false,
        &mut transfer,
@@ -801,13 +750,6 @@ async fn test_migrate_entry_version_transfer_retries_before_success() {
    assert_eq!(backend.get_calls(), 2);
    assert_eq!(transfer_count.load(Ordering::SeqCst), 2);
    assert_eq!(wait_count.load(Ordering::SeqCst), 1);
-    let read_opts = backend.last_get_opts();
-    assert_eq!(read_opts.version_id.as_deref(), version.version_id.map(|id| id.to_string()).as_deref());
-    assert!(read_opts.no_lock);
-    assert!(read_opts.data_movement);
-    assert!(read_opts.raw_data_movement_read);
-    assert!(read_opts.skip_decommissioned);
-    assert!(read_opts.skip_rebalancing);
 }

 #[tokio::test]
@@ -880,7 +822,6 @@ async fn test_migrate_entry_version_transfer_fails_after_retries() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        2,
        false,
        &mut transfer,
@@ -919,7 +860,6 @@ async fn test_migrate_entry_version_transfer_not_found_is_ignored() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -961,7 +901,6 @@ async fn test_migrate_entry_version_transfer_overwrite_is_not_ignored() {
        1,
        &version,
        Some("vid-1".to_string()),
-        None,
        3,
        false,
        &mut transfer,
@@ -1004,7 +943,6 @@ async fn test_migrate_entry_version_ignores_data_usage_cache_when_enabled() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        2,
        true,
        &mut transfer,
@@ -1047,7 +985,6 @@ async fn test_migrate_entry_version_data_usage_cache_moves_when_ignore_disabled(
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        2,
        false,
        &mut transfer,
@@ -2089,7 +2026,6 @@ async fn test_migrate_entry_version_transfer_failure_reports_write_target_stage(
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        1,
        false,
        &mut transfer,
@@ -2114,7 +2050,6 @@ async fn test_migrate_entry_version_reader_failure_reports_read_source_stage() {
        1,
        &version,
        version.version_id.map(|v| v.to_string()),
-        None,
        1,
        false,
        &mut transfer,
@@ -36,7 +36,6 @@ pub type RStats = Vec<Arc<RebalanceStats>>;

 #[derive(Debug, Default)]
 pub(super) struct RebalanceBucketConfigs {
-    pub(super) bucket_incarnation_id: Option<uuid::Uuid>,
    pub(super) lifecycle_config: Option<s3s::dto::BucketLifecycleConfiguration>,
    pub(super) object_lock_config: Option<s3s::dto::ObjectLockConfiguration>,
    pub(super) replication_config: Option<(s3s::dto::ReplicationConfiguration, OffsetDateTime)>,
@@ -406,7 +406,6 @@ pub(super) async fn load_rebalance_bucket_configs(api: &ECStore, bucket: &str) -

    let expiry_configs = crate::bucket::lifecycle::get_expiry_configs(api, bucket).await?;
    Ok(RebalanceBucketConfigs {
-        bucket_incarnation_id: Some(api.bucket_incarnation_id_from_disk(bucket).await?),
        lifecycle_config: expiry_configs.lifecycle.map(|config| (*config).clone()),
        object_lock_config: expiry_configs.object_lock.map(|config| (*config).clone()),
        replication_config: resolve_rebalance_optional_bucket_config_result(
@@ -85,15 +85,6 @@ impl SetDisks {
        format!("{}/{}", Self::get_multipart_sha_dir(bucket, object), upload_uuid)
    }

-    pub(super) fn get_multipart_upload_dir(bucket: &str, object: &str, upload_id: &str, data_movement: bool) -> String {
-        let upload_dir = Self::get_upload_id_dir(bucket, object, upload_id);
-        if data_movement {
-            format!("{DATA_MOVEMENT_MULTIPART_PREFIX}/{upload_dir}")
-        } else {
-            upload_dir
-        }
-    }
-
    pub(super) fn get_multipart_sha_dir(bucket: &str, object: &str) -> String {
        let path = format!("{bucket}/{object}");
        let mut hasher = Sha256::new();
@@ -475,28 +466,6 @@ impl SetDisks {
        Self::find_file_info_in_quorum(metas, &mod_time, &etag, quorum)
    }

-    pub(crate) fn hydrate_selected_fileinfo_part_checksums(fi: &mut FileInfo) -> disk::error::Result<()> {
-        fi.hydrate_data_movement_part_checksums().map_err(DiskError::from)?;
-        for part in &fi.parts {
-            let Some(checksums) = part.checksums.as_ref() else {
-                continue;
-            };
-            let mut algorithms = HashSet::with_capacity(checksums.len());
-            for (name, value) in checksums {
-                let Some(checksum) = rustfs_rio::Checksum::new_from_string(name, value) else {
-                    return Err(DiskError::FileCorrupt);
-                };
-                if checksum.checksum_type.is(rustfs_rio::ChecksumType::MULTIPART) {
-                    return Err(DiskError::FileCorrupt);
-                }
-                if !algorithms.insert(checksum.checksum_type.base().0) {
-                    return Err(DiskError::FileCorrupt);
-                }
-            }
-        }
-        Ok(())
-    }
-
    fn update_hash_bytes(hasher: &mut Sha256, value: &[u8]) {
        hasher.update(value.len().to_le_bytes());
        hasher.update(value);
@@ -1110,25 +1079,6 @@ impl SetDisks {
        shuffled_disks
    }

-    pub(super) fn shuffle_disks_owned(mut disks: Vec<Option<DiskStore>>, distribution: &[usize]) -> Vec<Option<DiskStore>> {
-        if distribution.is_empty() {
-            return disks;
-        }
-
-        let mut shuffled_disks = vec![None; disks.len()];
-        for (index, disk) in disks.iter_mut().enumerate() {
-            let Some(slot) = distribution
-                .get(index)
-                .and_then(|block_index| block_index.checked_sub(1))
-                .filter(|slot| *slot < shuffled_disks.len())
-            else {
-                continue;
-            };
-            shuffled_disks[slot] = disk.take();
-        }
-        shuffled_disks
-    }
-
    pub(super) fn shuffle_check_parts(parts_errs: &[usize], distribution: &[usize]) -> Vec<usize> {
        if distribution.is_empty() {
            return parts_errs.to_vec();
@@ -1440,23 +1390,6 @@ mod tests {
        assert_eq!(owned_slots, expected_slots, "fallback disk slots must match the borrowing variant");
    }

-    #[tokio::test]
-    async fn owned_shuffle_preserves_fresh_put_metadata() {
-        let tempdir = tempfile::tempdir().expect("tempdir should be created");
-        let fi = FileInfo::new("bucket/object", 2, 1);
-        let parts = vec![fi.clone(); fi.erasure.distribution.len()];
-        let disks = shuffle_test_disks(&tempdir, parts.len()).await;
-
-        let (owned_disks, owned_parts) = SetDisks::shuffle_disks_and_parts_metadata_by_index_owned(disks, parts, &fi);
-
-        assert!(owned_disks.iter().all(Option::is_some), "fresh PUT must retain every online disk");
-        assert_eq!(
-            owned_parts,
-            vec![fi; owned_disks.len()],
-            "fresh PUT metadata with pending shard indexes must survive init fallback"
-        );
-    }
-
    // backlog#949: corrupt/adversarial distribution values (0 or > N) must not
    // trigger a `usize` underflow / out-of-bounds panic in the shuffle helpers.
    #[test]
@@ -1486,22 +1419,6 @@ mod tests {
        assert_eq!(result.len(), disks.len(), "output length must be preserved");
    }

-    #[tokio::test]
-    async fn owned_disk_shuffle_matches_borrowing_variant() {
-        let tempdir = tempfile::tempdir().expect("tempdir should be created");
-        let mut disks = shuffle_test_disks(&tempdir, 4).await;
-        disks[1] = None;
-        disks[3] = None;
-        let distribution = [3, 1, 4, 2];
-
-        let expected = SetDisks::shuffle_disks(&disks, &distribution);
-        let actual = SetDisks::shuffle_disks_owned(disks, &distribution);
-
-        let expected_slots = expected.iter().map(Option::is_some).collect::<Vec<_>>();
-        let actual_slots = actual.iter().map(Option::is_some).collect::<Vec<_>>();
-        assert_eq!(actual_slots, expected_slots, "owned shuffle must preserve disk placement");
-    }
-
    #[tokio::test]
    async fn shuffle_disks_and_parts_metadata_survives_corrupt_distribution() {
        let tempdir = tempfile::tempdir().expect("tempdir should be created");
@@ -542,8 +542,7 @@ impl SetDisks {

                let filter_by_etag = quorum_etag.is_some();
                match Self::pick_valid_fileinfo(&parts_metadata, quorum_mod_time, quorum_etag.clone(), read_quorum as usize) {
-                    Ok(mut latest_meta) => {
-                        Self::hydrate_selected_fileinfo_part_checksums(&mut latest_meta)?;
+                    Ok(latest_meta) => {
                        trace!(
                            event = EVENT_SET_DISK_HEAL,
                            component = LOG_COMPONENT_ECSTORE,
@@ -3171,11 +3170,10 @@ mod heal_result_report_tests {
            .await
            .expect("object should be written");

-        let snapshot = set
+        let (fi, _, _) = set
            .get_object_fileinfo(bucket, object, &opts, true, false)
            .await
            .expect("object metadata should resolve");
-        let fi = snapshot.fi();
        assert_eq!(fi.erasure.parity_blocks, 0);
        let data_dir = fi.data_dir.expect("non-inline object should have a data directory");
        let part_path = dir.path().join(bucket).join(object).join(data_dir.to_string()).join("part.1");
@@ -36,21 +36,10 @@ impl crate::storage_api_contracts::namespace::NamespaceLocking for SetDisks {
        // test's transient DistErasure window) would push this set's namespace
        // locking onto its own — possibly empty — dist locker list.
        let set_lock = if self.ctx.is_dist_erasure().await {
-            let lockers = if self.lockers.len() == self.shared_lockers.len()
-                && self
-                    .lockers
-                    .iter()
-                    .zip(self.shared_lockers.iter())
-                    .all(|(current, shared)| Arc::ptr_eq(current, shared))
-            {
-                self.shared_lockers.clone()
-            } else {
-                Arc::from(self.lockers.clone())
-            };
-            // Calculate quorum from the exact client domain used by this lock.
-            let lockers_count = lockers.len();
+            // Calculate quorum based on lockers count (majority)
+            let lockers_count = self.lockers.len();
            let write_quorum = if lockers_count > 1 { (lockers_count / 2) + 1 } else { 1 };
-            NamespaceLock::with_clients_and_quorum_shared(self.set_lock_namespace.clone(), lockers, write_quorum)
+            NamespaceLock::with_clients_and_quorum_shared(self.set_lock_namespace.clone(), self.lockers.clone(), write_quorum)
        } else {
            NamespaceLock::with_local_manager_shared(self.set_lock_namespace.clone(), self.local_lock_manager.clone())
        };
@@ -19,7 +19,7 @@ use crate::diagnostics::get::{
    GET_METADATA_CACHE_REASON_DATA_MOVEMENT, GET_METADATA_CACHE_REASON_DELETE_MARKER, GET_METADATA_CACHE_REASON_DIST_ERASURE,
    GET_METADATA_CACHE_REASON_INCL_FREE_VERSIONS, GET_METADATA_CACHE_REASON_INSUFFICIENT_CACHED_QUORUM,
    GET_METADATA_CACHE_REASON_META_BUCKET, GET_METADATA_CACHE_REASON_NO_LOCK, GET_METADATA_CACHE_REASON_NOT_FOUND_OR_EXPIRED,
-    GET_METADATA_CACHE_REASON_NOT_READ_DATA, GET_METADATA_CACHE_REASON_PART_CHECKSUMS, GET_METADATA_CACHE_REASON_PART_NUMBER,
+    GET_METADATA_CACHE_REASON_NOT_READ_DATA, GET_METADATA_CACHE_REASON_PART_NUMBER,
    GET_METADATA_CACHE_REASON_RAW_DATA_MOVEMENT_READ, GET_METADATA_CACHE_REASON_STALE_PUBLICATION,
    GET_METADATA_CACHE_REASON_USABLE, GET_METADATA_CACHE_REASON_VERSION_ID, GET_METADATA_CACHE_REASON_VERSION_SUSPENDED,
    GET_METADATA_CACHE_REASON_VERSIONED, GET_METADATA_EARLY_STOP_REASON_CONFLICTING_METADATA,
@@ -180,9 +180,9 @@ impl SetDisks {
        let key = GetObjectMetadataCacheKey::new(bucket, object, generation);
        let entry = Arc::new(GetObjectMetadataCacheEntry {
            created_at: Instant::now(),
-            fi: fi.clone(),
-            parts_metadata: parts_metadata.to_vec(),
-            online_disks: online_disks.to_vec(),
+            fi: Arc::new(fi.clone()),
+            parts_metadata: Arc::new(parts_metadata.to_vec()),
+            online_disks: Arc::new(online_disks.to_vec()),
            read_quorum,
        });
        self.insert_get_object_metadata_cache_entry_after_insert(key, generation, entry, || {})
@@ -300,7 +300,11 @@ impl SetDisks {
                        GET_STAGE_METADATA_CACHE_LOOKUP,
                        metadata_cache_lookup_start,
                    );
-                    return Ok(GetObjectFileInfo::shared(cached));
+                    return Ok((
+                        GetObjectMetadata::Shared(Arc::clone(&cached.fi)),
+                        GetObjectMetadata::Shared(Arc::clone(&cached.parts_metadata)),
+                        GetObjectMetadata::Shared(Arc::clone(&cached.online_disks)),
+                    ));
                }
                MetadataCacheLookup::Miss => {
                    rustfs_io_metrics::record_get_object_metadata_cache_decision(
@@ -336,7 +340,7 @@ impl SetDisks {
        // read_all_fileinfo_observed (see read_all_fileinfo_early_stop in
        // core/io_primitives.rs); unsafe requests and callers that opt out
        // (allow_early_stop=false) fall back to full-wait.
-        let (mut parts_metadata, errs, metadata_fanout_diagnostics) = Self::read_all_fileinfo_observed(
+        let (parts_metadata, errs, metadata_fanout_diagnostics) = Self::read_all_fileinfo_observed(
            &disks,
            "",
            bucket,
@@ -390,17 +394,8 @@ impl SetDisks {
            return Err(to_object_err(err.into(), vec![bucket, object]));
        }

-        let (op_online_disks, mut fi, fileinfo_selection_quorum) =
+        let (op_online_disks, fi, fileinfo_selection_quorum) =
            Self::select_valid_fileinfo(&disks, &parts_metadata, &errs, vid.as_str(), read_quorum, write_quorum)?;
-        let include_part_checksums =
-            opts.include_part_checksums || opts.part_number.is_some() || opts.data_movement || opts.raw_data_movement_read;
-        if include_part_checksums {
-            Self::hydrate_selected_fileinfo_part_checksums(&mut fi)?;
-        } else {
-            for metadata in std::iter::once(&mut fi).chain(parts_metadata.iter_mut()) {
-                rustfs_utils::http::remove_str(&mut metadata.metadata, rustfs_utils::http::SUFFIX_PART_CHECKSUMS);
-            }
-        }
        metadata_fanout_diagnostics.record_quorum_candidate_latency(metadata_metrics_path, fileinfo_selection_quorum);
        if errs.iter().any(|err| err.is_some()) {
            let version_id = resolved_read_repair_version_id(&fi, opts.version_id.as_deref());
@@ -432,7 +427,11 @@ impl SetDisks {

        // let online_disks: Vec<Option<DiskStore>> = op_online_disks.iter().filter(|v| v.is_some()).cloned().collect();

-        Ok(GetObjectFileInfo::owned(fi, parts_metadata, op_online_disks))
+        Ok((
+            GetObjectMetadata::Owned(fi),
+            GetObjectMetadata::Owned(parts_metadata),
+            GetObjectMetadata::Owned(op_online_disks),
+        ))
    }

    #[hotpath::measure(impl_type = "SetDisks")]
@@ -442,15 +441,14 @@ impl SetDisks {
        object: &str,
        opts: &ObjectOptions,
    ) -> (ObjectInfo, usize, Option<StorageError>) {
-        let snapshot = match self.get_object_fileinfo(bucket, object, opts, false, false).await {
-            Ok(snapshot) => snapshot,
+        let fi = match self.get_object_fileinfo(bucket, object, opts, false, false).await {
+            Ok((fi, _, _)) => fi,
            Err(e) => return (ObjectInfo::default(), 0, Some(e)),
        };
-        let fi = snapshot.fi();

        let write_quorum = fi.write_quorum(self.default_write_quorum());

-        let oi = ObjectInfo::from_file_info(fi, bucket, object, opts.versioned || opts.version_suspended);
+        let oi = ObjectInfo::from_file_info(&fi, bucket, object, opts.versioned || opts.version_suspended);

        if !fi.version_purge_status().is_empty() && opts.version_id.is_some() {
            return (
@@ -482,7 +480,6 @@ impl SetDisks {
    pub(super) async fn try_get_object_direct_data_shards_with_fileinfo(
        bucket: &str,
        object: &str,
-        erasure_cache: Arc<ErasureCache>,
        fi: &FileInfo,
        files: &[FileInfo],
        disks: &[Option<DiskStore>],
@@ -503,7 +500,13 @@ impl SetDisks {
            return Ok(None);
        }

-        let erasure = erasure_cache.get_for_file_info(fi)?;
+        let erasure = coding::Erasure::try_new_with_options(
+            fi.erasure.data_blocks,
+            fi.erasure.parity_blocks,
+            fi.erasure.block_size,
+            fi.uses_legacy_checksum,
+        )
+        .map_err(Error::from)?;

        let checksum_info = fi.erasure.get_checksum_info(part.number);
        let checksum_algo = if fi.uses_legacy_checksum && checksum_info.algorithm == HashAlgorithm::HighwayHash256S {
@@ -631,7 +634,6 @@ impl SetDisks {
        // &self,
        bucket: &str,
        object: &str,
-        erasure_cache: Arc<ErasureCache>,
        offset: usize,
        length: i64,
        writer: &mut W,
@@ -726,7 +728,13 @@ impl SetDisks {
            object, offset, length, end_offset, part_index, last_part_index, last_part_relative_offset, "Multipart read bounds"
        );

-        let erasure = erasure_cache.get_for_file_info(&fi)?;
+        let erasure = coding::Erasure::try_new_with_options(
+            fi.erasure.data_blocks,
+            fi.erasure.parity_blocks,
+            fi.erasure.block_size,
+            fi.uses_legacy_checksum,
+        )
+        .map_err(Error::from)?;

        let part_indices: Vec<usize> = (part_index..=last_part_index).collect();
        debug!(bucket, object, ?part_indices, "Multipart part indices to stream");
@@ -1160,7 +1168,6 @@ impl SetDisks {
    pub(super) async fn get_object_decode_reader_with_fileinfo(
        bucket: &str,
        object: &str,
-        erasure_cache: Arc<ErasureCache>,
        fi: &FileInfo,
        files: &[FileInfo],
        disks: &[Option<DiskStore>],
@@ -1171,7 +1178,14 @@ impl SetDisks {
        metrics_size_bucket: &'static str,
        prefer_data_blocks_first_reader_setup: bool,
    ) -> Result<GetCodecStreamingReaderBuildOutcome> {
-        let erasure = erasure_cache.get_for_file_info(fi)?;
+        let erasure = coding::Erasure::try_new_with_options(
+            fi.erasure.data_blocks,
+            fi.erasure.parity_blocks,
+            fi.erasure.block_size,
+            fi.uses_legacy_checksum,
+        )
+        .map_err(Error::from)?;
+
        let (disks, files) = Self::shuffle_disks_and_parts_metadata_by_index(disks, files, fi);

        if fi.parts.len() == 1 {
@@ -1558,7 +1572,7 @@ struct LazyCodecPartContext {
    fi: FileInfo,
    files: Vec<FileInfo>,
    disks: Vec<Option<DiskStore>>,
-    erasure: Arc<coding::Erasure>,
+    erasure: coding::Erasure,
    skip_verify_bitrot: bool,
    metrics_object_class: &'static str,
    metrics_size_bucket: &'static str,
@@ -1812,9 +1826,6 @@ fn get_object_metadata_cache_request_bypass_reason(bucket: &str, opts: &ObjectOp
    if opts.part_number.is_some() {
        return Some(GET_METADATA_CACHE_REASON_PART_NUMBER);
    }
-    if opts.include_part_checksums {
-        return Some(GET_METADATA_CACHE_REASON_PART_CHECKSUMS);
-    }
    if opts.data_movement {
        return Some(GET_METADATA_CACHE_REASON_DATA_MOVEMENT);
    }
@@ -2042,7 +2053,6 @@ mod metadata_cache_tests {
        let err = SetDisks::get_object_with_fileinfo(
            "bucket",
            "object",
-            Arc::new(ErasureCache::new()),
            0,
            1,
            &mut output,
@@ -2073,7 +2083,6 @@ mod metadata_cache_tests {
        let err = SetDisks::get_object_with_fileinfo(
            bucket,
            object,
-            Arc::new(ErasureCache::new()),
            2,
            1,
            &mut output,
@@ -2097,7 +2106,6 @@ mod metadata_cache_tests {
        let err = SetDisks::get_object_with_fileinfo(
            bucket,
            object,
-            Arc::new(ErasureCache::new()),
            usize::MAX,
            1,
            &mut output,
@@ -2119,7 +2127,6 @@ mod metadata_cache_tests {
        let err = SetDisks::get_object_with_fileinfo(
            bucket,
            object,
-            Arc::new(ErasureCache::new()),
            1,
            1,
            &mut output,
@@ -2143,7 +2150,6 @@ mod metadata_cache_tests {
        let err = SetDisks::get_object_with_fileinfo(
            bucket,
            object,
-            Arc::new(ErasureCache::new()),
            0,
            1,
            &mut output,
@@ -2181,7 +2187,6 @@ mod metadata_cache_tests {
        SetDisks::get_object_with_fileinfo(
            bucket,
            object,
-            Arc::new(ErasureCache::new()),
            0,
            0,
            &mut output,
@@ -2214,7 +2219,6 @@ mod metadata_cache_tests {
        let err = SetDisks::get_object_with_fileinfo(
            bucket,
            object,
-            Arc::new(ErasureCache::new()),
            0,
            1,
            &mut output,
@@ -2493,16 +2497,6 @@ mod metadata_cache_tests {
            Some(GET_METADATA_CACHE_REASON_PART_NUMBER)
        );

-        opts = ObjectOptions {
-            include_part_checksums: true,
-            ..Default::default()
-        };
-        assert!(!is_get_object_metadata_cache_request_eligible("bucket", &opts, true));
-        assert_eq!(
-            get_object_metadata_cache_request_bypass_reason("bucket", &opts, true),
-            Some(GET_METADATA_CACHE_REASON_PART_CHECKSUMS)
-        );
-
        opts = ObjectOptions {
            data_movement: true,
            ..Default::default()
@@ -2707,14 +2701,22 @@ mod metadata_cache_tests {
            .await
            .expect("fresh cache entry should be returned");

-        let returned = set
+        let (returned_fi, returned_parts_metadata, returned_online_disks) = set
            .get_object_fileinfo("bucket", "object", &ObjectOptions::default(), true, false)
            .await
            .expect("cache-backed metadata lookup should succeed");

        assert!(
-            returned.shared_entry().is_some_and(|value| Arc::ptr_eq(value, &cached)),
-            "cache hits must share the complete metadata snapshot"
+            matches!(returned_fi, GetObjectMetadata::Shared(ref value) if Arc::ptr_eq(value, &cached.fi)),
+            "cache hits must share FileInfo ownership"
+        );
+        assert!(
+            matches!(returned_parts_metadata, GetObjectMetadata::Shared(ref value) if Arc::ptr_eq(value, &cached.parts_metadata)),
+            "cache hits must share the metadata vector"
+        );
+        assert!(
+            matches!(returned_online_disks, GetObjectMetadata::Shared(ref value) if Arc::ptr_eq(value, &cached.online_disks)),
+            "cache hits must share the online-disk vector"
        );
    }

@@ -2757,9 +2759,9 @@ mod metadata_cache_tests {
                ),
                Arc::new(GetObjectMetadataCacheEntry {
                    created_at: Instant::now(),
-                    fi: fi.clone(),
-                    parts_metadata: vec![fi],
-                    online_disks: vec![None],
+                    fi: Arc::new(fi.clone()),
+                    parts_metadata: Arc::new(vec![fi]),
+                    online_disks: Arc::new(vec![None]),
                    read_quorum: 1,
                }),
            )
@@ -2853,12 +2855,13 @@ mod metadata_cache_tests {
        barrier.wait_until_paused().await;
        set.invalidate_get_object_metadata_cache(bucket, object).await;
        barrier.release();
-        let snapshot = read
+        let (fi, parts_metadata, online_disks) = read
            .await
            .expect("metadata read task should not panic")
            .expect("metadata fanout should still return its selected FileInfo");
-        assert!(snapshot.owned.is_some());
-        assert!(snapshot.has_valid_representation());
+        assert!(matches!(fi, GetObjectMetadata::Owned(_)));
+        assert!(matches!(parts_metadata, GetObjectMetadata::Owned(_)));
+        assert!(matches!(online_disks, GetObjectMetadata::Owned(_)));

        assert!(
            set.get_object_metadata_cache
@@ -2905,9 +2908,9 @@ mod metadata_cache_tests {
        let key = GetObjectMetadataCacheKey::new("bucket", "object", generation);
        let entry = Arc::new(GetObjectMetadataCacheEntry {
            created_at: Instant::now(),
-            fi: fi.clone(),
-            parts_metadata: vec![fi],
-            online_disks: Vec::new(),
+            fi: Arc::new(fi.clone()),
+            parts_metadata: Arc::new(vec![fi]),
+            online_disks: Arc::new(Vec::new()),
            read_quorum: 0,
        });

@@ -3015,9 +3018,9 @@ mod metadata_cache_tests {
        let entry = |fi: FileInfo| {
            Arc::new(GetObjectMetadataCacheEntry {
                created_at: Instant::now(),
-                parts_metadata: vec![fi.clone()],
-                fi,
-                online_disks: Vec::new(),
+                parts_metadata: Arc::new(vec![fi.clone()]),
+                fi: Arc::new(fi),
+                online_disks: Arc::new(Vec::new()),
                read_quorum: 0,
            })
        };
@@ -4080,8 +4083,8 @@ mod tests {
        get_codec_streaming_reader_gate(
            CODEC_STREAMING_TEST_BUCKET,
            CODEC_STREAMING_TEST_OBJECT,
+            range,
            None,
-            classify_get_codec_streaming_object_class(range, object_info, fi),
            object_info,
            fi,
            lock_optimization_enabled,
@@ -4098,8 +4101,8 @@ mod tests {
        get_codec_streaming_reader_gate(
            CODEC_STREAMING_TEST_BUCKET,
            CODEC_STREAMING_TEST_OBJECT,
+            range,
            part_number,
-            classify_get_codec_streaming_object_class(range, object_info, fi),
            object_info,
            fi,
            lock_optimization_enabled,
@@ -4119,7 +4122,6 @@ mod tests {
        let result = SetDisks::get_object_decode_reader_with_fileinfo(
            CODEC_STREAMING_TEST_BUCKET,
            CODEC_STREAMING_TEST_OBJECT,
-            Arc::new(ErasureCache::new()),
            &fi,
            &[],
            &[],
@@ -4142,7 +4144,6 @@ mod tests {
        let invalid_size = SetDisks::get_object_decode_reader_with_fileinfo(
            CODEC_STREAMING_TEST_BUCKET,
            CODEC_STREAMING_TEST_OBJECT,
-            Arc::new(ErasureCache::new()),
            &single_part,
            &[],
            &[],
@@ -4163,7 +4164,6 @@ mod tests {
            SetDisks::get_object_decode_reader_with_fileinfo(
                CODEC_STREAMING_TEST_BUCKET,
                CODEC_STREAMING_TEST_OBJECT,
-                Arc::new(ErasureCache::new()),
                &multipart,
                &[],
                &[],
@@ -4188,7 +4188,6 @@ mod tests {
            SetDisks::get_object_decode_reader_with_fileinfo(
                CODEC_STREAMING_TEST_BUCKET,
                CODEC_STREAMING_TEST_OBJECT,
-                Arc::new(ErasureCache::new()),
                &multipart,
                &[],
                &[],
@@ -4217,7 +4216,6 @@ mod tests {
                SetDisks::get_object_decode_reader_with_fileinfo(
                    CODEC_STREAMING_TEST_BUCKET,
                    CODEC_STREAMING_TEST_OBJECT,
-                    Arc::new(ErasureCache::new()),
                    &multipart,
                    &[],
                    &[],
@@ -4271,7 +4269,6 @@ mod tests {
                SetDisks::get_object_decode_reader_with_fileinfo(
                    CODEC_STREAMING_TEST_BUCKET,
                    CODEC_STREAMING_TEST_OBJECT,
-                    Arc::new(ErasureCache::new()),
                    &fi,
                    &files,
                    &disks,
@@ -4325,7 +4322,6 @@ mod tests {
            SetDisks::get_object_decode_reader_with_fileinfo(
                CODEC_STREAMING_TEST_BUCKET,
                CODEC_STREAMING_TEST_OBJECT,
-                Arc::new(ErasureCache::new()),
                &fi,
                &files,
                &disks,
@@ -4370,7 +4366,6 @@ mod tests {
        SetDisks::get_object_with_fileinfo(
            CODEC_STREAMING_TEST_BUCKET,
            CODEC_STREAMING_TEST_OBJECT,
-            Arc::new(ErasureCache::new()),
            0,
            part_data.len() as i64,
            &mut output,
@@ -4833,114 +4828,6 @@ mod tests {
        .await
    }

-    async fn encoded_inline_blocks(blocks: &[&[u8]], shard_size: usize, hash_algo: HashAlgorithm) -> Bytes {
-        let mut writer = BitrotWriter::new(Cursor::new(Vec::new()), shard_size, hash_algo);
-        for block in blocks {
-            writer.write(block).await.expect("test block should be encoded");
-        }
-        Bytes::from(writer.into_inner().into_inner())
-    }
-
-    fn assert_reader_shares_inline_allocation(reader: &ObjectBitrotReader, source: &Bytes) {
-        let reader_bytes = reader
-            .inner_ref()
-            .inline_bytes()
-            .expect("inline scheduler should retain an in-memory Bytes source");
-        assert_eq!(
-            reader_bytes.as_ptr(),
-            source.as_ptr(),
-            "the scheduler must clone Bytes ownership instead of copying the inline shard payload"
-        );
-    }
-
-    #[tokio::test]
-    async fn inline_range_scheduler_shares_bytes_and_rejects_bitrot_mismatch() {
-        const SHARD_SIZE: usize = 16;
-        let hash_algo = HashAlgorithm::HighwayHash256S;
-        let first = [b'a'; SHARD_SIZE];
-        let second = [b'b'; SHARD_SIZE];
-        let mut source = encoded_inline_blocks(&[&first, &second], SHARD_SIZE, hash_algo.clone()).await;
-        let second_payload = hash_algo.size() * 2 + SHARD_SIZE;
-        source = {
-            let mut corrupt = source.to_vec();
-            corrupt[second_payload] ^= 0xff;
-            Bytes::from(corrupt)
-        };
-        let files = vec![encoded_reader_setup_fileinfo(Some(source.to_vec()))];
-        let source = files[0].data.clone().expect("inline shard should exist");
-        let disks = vec![None];
-
-        let mut setup = create_bitrot_readers_until_quorum_with_preference(
-            &files,
-            &disks,
-            "bucket",
-            "object",
-            1,
-            SHARD_SIZE,
-            SHARD_SIZE,
-            SHARD_SIZE,
-            hash_algo,
-            false,
-            false,
-            1,
-            0,
-            BitrotReaderSetupMode::ReadQuorum,
-            true,
-            None,
-            None,
-        )
-        .await;
-        let mut reader = setup.readers[0].take().expect("range reader should be ready");
-        assert_reader_shares_inline_allocation(&reader, &source);
-
-        let err = reader
-            .read(&mut [0; SHARD_SIZE])
-            .await
-            .expect_err("corrupt ranged inline block must fail bitrot verification");
-        assert_eq!(err.kind(), ErrorKind::InvalidData);
-    }
-
-    #[tokio::test]
-    async fn inline_part_scheduler_shares_bytes_and_rejects_bitrot_mismatch() {
-        const SHARD_SIZE: usize = 16;
-        let hash_algo = HashAlgorithm::HighwayHash256S;
-        let block = [b'p'; SHARD_SIZE];
-        let encoded = encoded_inline_blocks(&[&block], SHARD_SIZE, hash_algo.clone()).await;
-        let mut corrupt = encoded.to_vec();
-        corrupt[hash_algo.size()] ^= 0xff;
-        let files = vec![encoded_reader_setup_fileinfo(Some(corrupt))];
-        let source = files[0].data.clone().expect("inline shard should exist");
-        let disks = vec![None];
-
-        let mut setup = create_bitrot_readers_until_quorum_all_shards(
-            &files,
-            &disks,
-            "bucket",
-            "object",
-            7,
-            0,
-            SHARD_SIZE,
-            SHARD_SIZE,
-            hash_algo,
-            false,
-            false,
-            1,
-            0,
-            BitrotReaderSetupMode::VerifyReconstruction,
-            None,
-            None,
-        )
-        .await;
-        let mut reader = setup.readers[0].take().expect("part reader should be ready");
-        assert_reader_shares_inline_allocation(&reader, &source);
-
-        let err = reader
-            .read(&mut [0; SHARD_SIZE])
-            .await
-            .expect_err("corrupt inline part must fail bitrot verification");
-        assert_eq!(err.kind(), ErrorKind::InvalidData);
-    }
-
    async fn decode_codec_data_blocks_first_setup(
        erasure: coding::Erasure,
        data: &[u8],
@@ -5641,63 +5528,6 @@ mod tests {
        });
    }

-    #[test]
-    fn codec_streaming_config_cache_loads_once() {
-        use std::cell::Cell;
-
-        let loads = Cell::new(0);
-        let expected = GetCodecStreamingConfig {
-            enabled: true,
-            rollout: GetCodecStreamingRollout::Off,
-            rollout_pct: 100,
-            body_compat_confirmed: true,
-            header_compat_confirmed: true,
-            engine: GetCodecStreamingEngine::Legacy,
-            min_size: DEFAULT_RUSTFS_GET_CODEC_STREAMING_MIN_SIZE,
-        };
-
-        for _ in 0..3 {
-            assert_eq!(
-                get_codec_streaming_config_cached_core(|| {
-                    loads.set(loads.get() + 1);
-                    expected
-                }),
-                expected
-            );
-        }
-        assert_eq!(loads.get(), 1, "production config cache must not reload env per GET");
-    }
-
-    #[test]
-    fn codec_streaming_config_loader_preserves_all_gate_env_overrides() {
-        temp_env::with_vars(
-            [
-                (ENV_RUSTFS_GET_CODEC_STREAMING_ENABLE, Some("false")),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_ENGINE, Some(GET_CODEC_STREAMING_ENGINE_RUSTFS)),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_ROLLOUT, Some("production")),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_ROLLOUT_PCT, Some("37")),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_BODY_COMPAT_CONFIRMED, Some("false")),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_HEADER_COMPAT_CONFIRMED, Some("false")),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_MIN_SIZE, None::<&str>),
-                (ENV_RUSTFS_GET_CODEC_STREAMING_RUSTFS_MIN_SIZE, Some("262144")),
-            ],
-            || {
-                assert_eq!(
-                    load_get_codec_streaming_config(),
-                    GetCodecStreamingConfig {
-                        enabled: false,
-                        rollout: GetCodecStreamingRollout::On,
-                        rollout_pct: 37,
-                        body_compat_confirmed: false,
-                        header_compat_confirmed: false,
-                        engine: GetCodecStreamingEngine::Rustfs,
-                        min_size: 262144,
-                    }
-                );
-            },
-        );
-    }
-
    #[test]
    fn codec_streaming_default_min_size_meets_direct_memory_ceiling() {
        for engine in [None, Some(GET_CODEC_STREAMING_ENGINE_RUSTFS)] {
@@ -75,13 +75,12 @@ impl SetDisks {
            version_id,
            versioned: opts.versioned,
            version_suspended: opts.version_suspended,
-            include_part_checksums: true,
            ..Default::default()
        };
-        let (mut fi, _, disks) = self
+        let (fi, _, disks) = self
            .get_object_fileinfo_gated(bucket, object, &read_opts, false, false)
-            .await?
-            .into_owned();
+            .await?;
+        let mut fi = fi.into_owned();
        if let Some(expected_operation_id) = expected_operation_id {
            require_restore_operation_id(&fi.metadata, expected_operation_id)?;
        }
@@ -143,13 +142,12 @@ impl SetDisks {
            version_id,
            versioned: opts.versioned,
            version_suspended: opts.version_suspended,
-            include_part_checksums: true,
            ..Default::default()
        };
-        let (mut fi, _, disks) = self
+        let (fi, _, disks) = self
            .get_object_fileinfo_gated(bucket, object, &read_opts, false, false)
-            .await?
-            .into_owned();
+            .await?;
+        let mut fi = fi.into_owned();
        if let Some(expected_operation_id) = expected_operation_id {
            match restore_operation_id_from_metadata(&fi.metadata)? {
                Some(actual_operation_id) if actual_operation_id == expected_operation_id => {}
@@ -16,14 +16,6 @@ use crate::diagnostics::get::{
    GET_SHARD_READ_COST_LOCAL, GET_SHARD_READ_COST_REMOTE, GET_SHARD_READ_COST_SAME_NODE, GET_SHARD_READ_COST_UNKNOWN,
 };
 use crate::disk::error::Error;
-use crate::layout::disks_layout::MAX_ERASURE_SET_DRIVE_COUNT;
-use smallvec::SmallVec;
-
-/// Generic codec callers may exceed the production set limit; `SmallVec` then
-/// spills without changing slot semantics.
-pub(crate) const INLINE_SHARD_SLOTS: usize = MAX_ERASURE_SET_DRIVE_COUNT;
-pub(crate) type ShardBuffers = SmallVec<[Option<Vec<u8>>; INLINE_SHARD_SLOTS]>;
-pub(crate) type ShardErrors = SmallVec<[Option<Error>; INLINE_SHARD_SLOTS]>;

 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum ShardReadCost {
@@ -51,137 +43,202 @@ impl ShardReadCost {
    }
 }

+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) struct ShardSlot {
+    index: usize,
+    read_cost: ShardReadCost,
+    data: Option<Vec<u8>>,
+    error: Option<Error>,
+}
+
+impl ShardSlot {
+    pub(crate) fn new(index: usize, data: Option<Vec<u8>>, error: Option<Error>) -> Self {
+        Self::with_read_cost(index, ShardReadCost::Unknown, data, error)
+    }
+
+    pub(crate) fn with_read_cost(index: usize, read_cost: ShardReadCost, data: Option<Vec<u8>>, error: Option<Error>) -> Self {
+        Self {
+            index,
+            read_cost,
+            data,
+            error,
+        }
+    }
+
+    pub(crate) fn data(index: usize, data: Vec<u8>) -> Self {
+        Self::new(index, Some(data), None)
+    }
+
+    pub(crate) fn data_with_read_cost(index: usize, read_cost: ShardReadCost, data: Vec<u8>) -> Self {
+        Self::with_read_cost(index, read_cost, Some(data), None)
+    }
+
+    pub(crate) fn missing(index: usize, error: Error) -> Self {
+        Self::new(index, None, Some(error))
+    }
+
+    pub(crate) fn missing_with_read_cost(index: usize, read_cost: ShardReadCost, error: Error) -> Self {
+        Self::with_read_cost(index, read_cost, None, Some(error))
+    }
+
+    pub(crate) fn index(&self) -> usize {
+        self.index
+    }
+
+    pub(crate) fn read_cost(&self) -> ShardReadCost {
+        self.read_cost
+    }
+
+    pub(crate) fn has_data(&self) -> bool {
+        self.data.is_some()
+    }
+
+    pub(crate) fn data_bytes(&self) -> Option<&[u8]> {
+        self.data.as_deref()
+    }
+
+    pub(crate) fn error(&self) -> Option<&Error> {
+        self.error.as_ref()
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub(crate) struct StripeReadState {
-    shards: ShardBuffers,
-    errors: ShardErrors,
+    slots: Vec<ShardSlot>,
    read_quorum: usize,
 }

 impl StripeReadState {
-    #[cfg(test)]
+    pub(crate) fn new(slots: Vec<ShardSlot>, read_quorum: usize) -> Self {
+        Self { slots, read_quorum }
+    }
+
    pub(crate) fn from_parts(shards: Vec<Option<Vec<u8>>>, errors: Vec<Option<Error>>, read_quorum: usize) -> Self {
-        let mut shards = SmallVec::from_vec(shards);
-        let mut errors = SmallVec::from_vec(errors);
+        Self::from_parts_with_read_costs(shards, errors, &[], read_quorum)
+    }
+
+    pub(crate) fn from_parts_with_read_costs<S, E>(shards: S, errors: E, read_costs: &[ShardReadCost], read_quorum: usize) -> Self
+    where
+        S: IntoIterator<Item = Option<Vec<u8>>>,
+        S::IntoIter: ExactSizeIterator,
+        E: IntoIterator<Item = Option<Error>>,
+        E::IntoIter: ExactSizeIterator,
+    {
+        let mut shards = shards.into_iter();
+        let mut errors = errors.into_iter();
        let slot_count = shards.len().max(errors.len());
-        shards.resize_with(slot_count, || None);
-        errors.resize_with(slot_count, || None);
-        Self {
-            shards,
-            errors,
-            read_quorum,
+        let mut slots = Vec::with_capacity(slot_count);
+        for index in 0..slot_count {
+            let read_cost = read_costs.get(index).copied().unwrap_or(ShardReadCost::Unknown);
+            slots.push(ShardSlot::with_read_cost(
+                index,
+                read_cost,
+                shards.next().flatten(),
+                errors.next().flatten(),
+            ));
        }
-    }
-
-    pub(crate) fn with_slot_count(slot_count: usize, read_quorum: usize) -> Self {
-        let mut state = Self {
-            shards: SmallVec::new(),
-            errors: SmallVec::new(),
-            read_quorum,
-        };
-        state.reset(slot_count, read_quorum);
-        state
-    }
-
-    pub(crate) fn reset(&mut self, slot_count: usize, read_quorum: usize) {
-        self.shards.clear();
-        self.shards.resize_with(slot_count, || None);
-        self.errors.clear();
-        self.errors.resize_with(slot_count, || None);
-        self.read_quorum = read_quorum;
+        Self::new(slots, read_quorum)
    }

    pub(crate) fn available_shards(&self) -> usize {
-        self.shards.iter().filter(|shard| shard.is_some()).count()
+        self.slots.iter().filter(|slot| slot.has_data()).count()
    }

    pub(crate) fn can_decode(&self) -> bool {
        self.available_shards() >= self.read_quorum
    }

-    pub(crate) fn is_empty(&self) -> bool {
-        self.shards.is_empty()
+    pub(crate) fn slots(&self) -> &[ShardSlot] {
+        &self.slots
    }

-    pub(crate) fn data_bytes(&self, index: usize) -> Option<&[u8]> {
-        self.shards.get(index).and_then(Option::as_deref)
-    }
-
-    #[cfg(test)]
-    pub(crate) fn error(&self, index: usize) -> Option<&Error> {
-        self.errors.get(index).and_then(Option::as_ref)
+    pub(crate) fn slot_by_index(&self, index: usize) -> Option<&ShardSlot> {
+        if let Some(slot) = self.slots.get(index)
+            && slot.index == index
+        {
+            return Some(slot);
+        }
+        self.slots.iter().find(|slot| slot.index == index)
    }

    pub(crate) fn data_shards_complete(&self, data_shards: usize) -> bool {
-        self.shards.len() >= data_shards && self.shards.iter().take(data_shards).all(Option::is_some)
+        (0..data_shards).all(|index| self.slot_by_index(index).is_some_and(ShardSlot::has_data))
    }

-    pub(crate) fn parts_mut(&mut self) -> (&mut ShardBuffers, &mut ShardErrors) {
-        (&mut self.shards, &mut self.errors)
-    }
-
-    pub(crate) fn shards_mut(&mut self) -> &mut ShardBuffers {
-        &mut self.shards
-    }
-
-    pub(crate) fn into_parts(self) -> (ShardBuffers, ShardErrors) {
-        (self.shards, self.errors)
-    }
-
-    #[cfg(test)]
-    pub(crate) fn scratch_storage(&self) -> (*const Option<Vec<u8>>, *const Option<Error>, bool, bool) {
-        (self.shards.as_ptr(), self.errors.as_ptr(), self.shards.spilled(), self.errors.spilled())
-    }
-
-    #[cfg(test)]
-    pub(crate) fn shard_allocation(&self, index: usize) -> Option<(*const u8, usize)> {
-        self.shards
-            .get(index)
-            .and_then(|shard| shard.as_ref().map(|shard| (shard.as_ptr(), shard.capacity())))
+    pub(crate) fn into_parts(self) -> (Vec<Option<Vec<u8>>>, Vec<Option<Error>>) {
+        let part_count = self.slots.iter().map(|slot| slot.index).max().map_or(0, |index| index + 1);
+        let mut shards = Vec::with_capacity(part_count);
+        shards.resize_with(part_count, || None);
+        let mut errors = Vec::with_capacity(part_count);
+        errors.resize_with(part_count, || None);
+        for slot in self.slots {
+            shards[slot.index] = slot.data;
+            errors[slot.index] = slot.error;
+        }
+        (shards, errors)
    }
 }

 #[async_trait::async_trait]
 pub(crate) trait ShardStripeSource: Send {
-    async fn read_next_stripe(&mut self) -> Box<StripeReadState>;
-
-    fn recycle_stripe(&mut self, _state: Box<StripeReadState>) {}
+    async fn read_next_stripe(&mut self) -> StripeReadState;
 }

 #[cfg(test)]
 mod tests {
    use super::*;
-    use std::mem::size_of;

    #[test]
-    fn stripe_scratch_capacity_matches_the_production_set_limit() {
-        type OversizedShardBuffers = SmallVec<[Option<Vec<u8>>; 32]>;
-        type OversizedShardErrors = SmallVec<[Option<Error>; 32]>;
-
-        assert_eq!(INLINE_SHARD_SLOTS, MAX_ERASURE_SET_DRIVE_COUNT);
-        assert!(size_of::<ShardBuffers>() < size_of::<OversizedShardBuffers>());
-        assert!(size_of::<ShardErrors>() < size_of::<OversizedShardErrors>());
-    }
-
-    #[test]
-    fn stripe_read_state_tracks_decode_quorum_and_slot_access() {
-        let state =
-            StripeReadState::from_parts(vec![Some(vec![1]), None, Some(vec![2])], vec![None, Some(Error::FileNotFound), None], 2);
+    fn stripe_read_state_tracks_decode_quorum() {
+        let state = StripeReadState::new(
+            vec![
+                ShardSlot::data_with_read_cost(0, ShardReadCost::Local, vec![1]),
+                ShardSlot::missing_with_read_cost(1, ShardReadCost::Remote, Error::FileNotFound),
+                ShardSlot::data_with_read_cost(2, ShardReadCost::SameNode, vec![2]),
+            ],
+            2,
+        );

        assert_eq!(state.available_shards(), 2);
        assert!(state.can_decode());
-        assert_eq!(state.data_bytes(0), Some(&[1][..]));
-        assert_eq!(state.error(1), Some(&Error::FileNotFound));
+        assert_eq!(state.slots()[1].index(), 1);
+        assert_eq!(state.slots()[0].read_cost(), ShardReadCost::Local);
+        assert!(state.slots()[2].read_cost().is_low_cost());
    }

    #[test]
    fn stripe_read_state_preserves_shards_and_errors() {
-        let state = StripeReadState::from_parts(vec![Some(vec![1, 2, 3]), None], vec![None, Some(Error::FileCorrupt)], 2);
+        let state = StripeReadState::new(vec![ShardSlot::missing(1, Error::FileCorrupt), ShardSlot::data(0, vec![1, 2, 3])], 2);

        assert!(!state.can_decode());
        let (shards, errors) = state.into_parts();
-        assert_eq!(shards.as_slice(), &[Some(vec![1, 2, 3]), None]);
-        assert_eq!(errors.as_slice(), &[None, Some(Error::FileCorrupt)]);
+        assert_eq!(shards, vec![Some(vec![1, 2, 3]), None]);
+        assert_eq!(errors, vec![None, Some(Error::FileCorrupt)]);
+    }
+
+    #[test]
+    fn stripe_read_state_builds_slots_from_parallel_reader_parts() {
+        let state =
+            StripeReadState::from_parts(vec![Some(vec![1]), None, Some(vec![3])], vec![None, Some(Error::FileNotFound)], 2);
+
+        assert!(state.can_decode());
+        assert_eq!(state.slots()[1].index(), 1);
+        assert_eq!(state.slots()[1].error(), Some(&Error::FileNotFound));
+    }
+
+    #[test]
+    fn stripe_read_state_preserves_read_cost_hints() {
+        let state = StripeReadState::from_parts_with_read_costs(
+            vec![Some(vec![1]), None, Some(vec![3])],
+            vec![None, Some(Error::FileNotFound)],
+            &[ShardReadCost::Local, ShardReadCost::Remote, ShardReadCost::Unknown],
+            2,
+        );
+
+        assert_eq!(state.slots()[0].read_cost(), ShardReadCost::Local);
+        assert_eq!(state.slots()[1].read_cost(), ShardReadCost::Remote);
+        assert_eq!(state.slots()[2].read_cost(), ShardReadCost::Unknown);
+        assert_eq!(ShardReadCost::SameNode.as_str(), GET_SHARD_READ_COST_SAME_NODE);
    }

    #[test]
@@ -201,8 +258,8 @@ mod tests {
        let state = StripeReadState::from_parts(vec![Some(vec![1]), Some(vec![2]), None], Vec::new(), 2);

        assert!(state.data_shards_complete(2));
-        assert_eq!(state.data_bytes(0), Some(&[1][..]));
-        assert_eq!(state.data_bytes(1), Some(&[2][..]));
+        assert_eq!(state.slots()[0].data_bytes(), Some(&[1][..]));
+        assert_eq!(state.slot_by_index(1).and_then(ShardSlot::data_bytes), Some(&[2][..]));
    }

    #[test]
@@ -211,4 +268,12 @@ mod tests {

        assert!(!state.data_shards_complete(2));
    }
+
+    #[test]
+    fn stripe_read_state_finds_out_of_order_slots_by_index() {
+        let state = StripeReadState::new(vec![ShardSlot::data(2, vec![3]), ShardSlot::data(0, vec![1])], 2);
+
+        assert_eq!(state.slot_by_index(0).and_then(ShardSlot::data_bytes), Some(&[1][..]));
+        assert!(state.slot_by_index(1).is_none());
+    }
 }
@@ -161,10 +161,6 @@ impl BucketIncarnationFenceGuard {
    pub(crate) fn is_lock_lost(&self) -> bool {
        self.inner.as_ref().is_some_and(NamespaceLockGuard::is_lock_lost)
    }
-
-    pub(crate) fn namespace_lock_guard(&self) -> Option<&NamespaceLockGuard> {
-        self.inner.as_ref()
-    }
 }

 impl Drop for BucketIncarnationFenceGuard {
@@ -309,17 +309,9 @@ const ENV_API_LIST_OBJECTS_INDEX_PROVIDER: &str = "RUSTFS_LIST_OBJECTS_INDEX_PRO
 const ENV_API_LIST_OBJECTS_INDEX_PROVIDER_PATH: &str = "RUSTFS_LIST_OBJECTS_INDEX_PROVIDER_PATH";
 const ENV_API_LIST_OBJECTS_INDEX_PROVIDER_GENERATION: &str = "RUSTFS_LIST_OBJECTS_INDEX_PROVIDER_GENERATION";
 const ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_PATH: &str = "RUSTFS_LIST_OBJECTS_NAMESPACE_JOURNAL_PATH";
-// The chaos machinery below is compiled only for tests and the opt-in
-// `list-chaos` feature (backlog#1832): a production binary without the
-// feature carries no chaos symbols, so the two env vars cannot silently
-// rewrite a bucket's namespace-journal state.
-#[cfg(any(test, feature = "list-chaos"))]
 const ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_ENABLED: &str = "RUSTFS_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_ENABLED";
-#[cfg(any(test, feature = "list-chaos"))]
 const ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_BUCKET: &str = "RUSTFS_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_BUCKET";
-#[cfg(any(test, feature = "list-chaos"))]
 const ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_SEQUENCE: &str = "RUSTFS_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_SEQUENCE";
-#[cfg(any(test, feature = "list-chaos"))]
 const ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_STATUS: &str = "RUSTFS_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_STATUS";
 const ENV_API_LIST_OBJECTS_METADATA_FAST_ENABLED: &str = "RUSTFS_LIST_OBJECTS_METADATA_FAST_ENABLED";
 const ENV_API_LIST_OBJECTS_METADATA_FAST_STALENESS_MS: &str = "RUSTFS_LIST_OBJECTS_METADATA_FAST_STALENESS_MS";
@@ -560,9 +552,7 @@ static LIST_OBJECTS_MUTATION_SEQUENCE: AtomicU64 = AtomicU64::new(0);
 static SCANNER_NAMESPACE_MUTATION_GENERATION: AtomicU64 = AtomicU64::new(0);
 static LIST_OBJECTS_BUCKET_MUTATION_SEQUENCE: OnceCell<RwLock<HashMap<String, u64>>> = OnceCell::const_new();
 static LIST_OBJECTS_NAMESPACE_JOURNAL_DEGRADED_BUCKETS: OnceCell<RwLock<HashSet<String>>> = OnceCell::const_new();
-#[cfg(any(test, feature = "list-chaos"))]
 static LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_CONFIG: OnceCell<Option<NamespaceMutationJournalChaosConfig>> = OnceCell::const_new();
-#[cfg(any(test, feature = "list-chaos"))]
 static LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_APPLIED: OnceCell<RwLock<HashSet<String>>> = OnceCell::const_new();

 async fn persistent_key_only_index_cache() -> &'static RwLock<Option<PersistentKeyOnlyIndexCache>> {
@@ -589,7 +579,6 @@ async fn list_objects_namespace_journal_degraded_buckets() -> &'static RwLock<Ha
        .await
 }

-#[cfg(any(test, feature = "list-chaos"))]
 async fn list_objects_namespace_journal_chaos_config() -> Option<&'static NamespaceMutationJournalChaosConfig> {
    LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_CONFIG
        .get_or_init(|| async { namespace_mutation_journal_chaos_config_from_env() })
@@ -597,7 +586,6 @@ async fn list_objects_namespace_journal_chaos_config() -> Option<&'static Namesp
        .as_ref()
 }

-#[cfg(any(test, feature = "list-chaos"))]
 async fn list_objects_namespace_journal_chaos_applied() -> &'static RwLock<HashSet<String>> {
    LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_APPLIED
        .get_or_init(|| async { RwLock::new(HashSet::new()) })
@@ -693,7 +681,6 @@ enum NamespaceMutationJournalStatus {
 }

 impl NamespaceMutationJournalStatus {
-    #[cfg(any(test, feature = "list-chaos"))]
    fn from_env_value(value: &str) -> Option<Self> {
        if value.eq_ignore_ascii_case(LIST_OBJECTS_NAMESPACE_JOURNAL_STATUS_HEALTHY) {
            Some(Self::Healthy)
@@ -704,7 +691,6 @@ impl NamespaceMutationJournalStatus {
        }
    }

-    #[cfg(any(test, feature = "list-chaos"))]
    fn env_value(self) -> &'static str {
        match self {
            Self::Healthy => LIST_OBJECTS_NAMESPACE_JOURNAL_STATUS_HEALTHY,
@@ -726,7 +712,6 @@ struct NamespaceMutationJournalSnapshot {
    degraded: bool,
 }

-#[cfg(any(test, feature = "list-chaos"))]
 #[derive(Debug, Clone, PartialEq, Eq)]
 struct NamespaceMutationJournalChaosConfig {
    bucket: String,
@@ -810,35 +795,30 @@ fn list_objects_namespace_journal_root_from_env() -> Option<PathBuf> {
        .filter(|path| !path.as_os_str().is_empty())
 }

-#[cfg(any(test, feature = "list-chaos"))]
 fn namespace_mutation_journal_chaos_enabled_from_env() -> bool {
    std::env::var(ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_ENABLED)
        .ok()
        .is_some_and(|value| value == "1" || value.eq_ignore_ascii_case("on") || value.eq_ignore_ascii_case("true"))
 }

-#[cfg(any(test, feature = "list-chaos"))]
 fn namespace_mutation_journal_chaos_bucket_from_env() -> Option<String> {
    std::env::var(ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_BUCKET)
        .ok()
        .filter(|bucket| !bucket.is_empty())
 }

-#[cfg(any(test, feature = "list-chaos"))]
 fn namespace_mutation_journal_chaos_sequence_from_env() -> Option<u64> {
    std::env::var(ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_SEQUENCE)
        .ok()
        .and_then(|value| value.parse::<u64>().ok())
 }

-#[cfg(any(test, feature = "list-chaos"))]
 fn namespace_mutation_journal_chaos_status_from_env() -> Option<NamespaceMutationJournalStatus> {
    std::env::var(ENV_API_LIST_OBJECTS_NAMESPACE_JOURNAL_CHAOS_STATUS)
        .ok()
        .and_then(|value| NamespaceMutationJournalStatus::from_env_value(&value))
 }

-#[cfg(any(test, feature = "list-chaos"))]
 fn namespace_mutation_journal_chaos_config_from_env() -> Option<NamespaceMutationJournalChaosConfig> {
    if !namespace_mutation_journal_chaos_enabled_from_env() {
        return None;
@@ -866,7 +846,6 @@ fn namespace_mutation_journal_chaos_config_from_env() -> Option<NamespaceMutatio
    })
 }

-#[cfg(any(test, feature = "list-chaos"))]
 fn namespace_mutation_journal_chaos_applied_key(bucket: &str, status: NamespaceMutationJournalStatus) -> String {
    let mut key = String::with_capacity(bucket.len() + 1 + status.env_value().len());
    key.push_str(bucket);
@@ -875,13 +854,6 @@ fn namespace_mutation_journal_chaos_applied_key(bucket: &str, status: NamespaceM
    key
 }

-/// Production no-op twin of the chaos injector: without `list-chaos` the
-/// injection point compiles to nothing (backlog#1832).
-#[cfg(not(any(test, feature = "list-chaos")))]
-#[inline]
-async fn maybe_apply_system_namespace_mutation_journal_chaos(_store: &ECStore, _bucket: &str, _default_sequence: u64) {}
-
-#[cfg(any(test, feature = "list-chaos"))]
 async fn maybe_apply_system_namespace_mutation_journal_chaos(store: &ECStore, bucket: &str, default_sequence: u64) {
    let Some(config) = list_objects_namespace_journal_chaos_config().await else {
        return;
@@ -389,7 +389,7 @@ impl crate::storage_api_contracts::object::ObjectIO for ECStore {
    type GetObjectReader = GetObjectReader;
    type PutObjectReader = PutObjReader;

-    #[instrument(level = "debug", skip(self, h))]
+    #[instrument(level = "debug", skip(self))]
    async fn get_object_reader(
        &self,
        bucket: &str,
@@ -66,76 +66,6 @@ fn ensure_multipart_bucket_lifecycle_guard_held(
    Ok(())
 }

-#[cfg(test)]
-struct DataMovementMultipartCompletionBarrierState {
-    bucket: String,
-    arrived: tokio::sync::Notify,
-    release: tokio::sync::Notify,
-}
-
-#[cfg(test)]
-pub(crate) struct DataMovementMultipartCompletionBarrier {
-    state: Arc<DataMovementMultipartCompletionBarrierState>,
-}
-
-#[cfg(test)]
-static DATA_MOVEMENT_MULTIPART_COMPLETION_BARRIER: std::sync::OnceLock<
-    std::sync::Mutex<Option<Arc<DataMovementMultipartCompletionBarrierState>>>,
-> = std::sync::OnceLock::new();
-
-#[cfg(test)]
-impl DataMovementMultipartCompletionBarrier {
-    pub(crate) fn install(bucket: &str) -> Self {
-        let state = Arc::new(DataMovementMultipartCompletionBarrierState {
-            bucket: bucket.to_string(),
-            arrived: tokio::sync::Notify::new(),
-            release: tokio::sync::Notify::new(),
-        });
-        let mut slot = DATA_MOVEMENT_MULTIPART_COMPLETION_BARRIER
-            .get_or_init(|| std::sync::Mutex::new(None))
-            .lock()
-            .expect("data movement multipart completion barrier mutex should not poison");
-        assert!(slot.is_none(), "data movement multipart completion barrier must be unique");
-        *slot = Some(Arc::clone(&state));
-        Self { state }
-    }
-
-    pub(crate) async fn wait_until_paused(&self) {
-        tokio::time::timeout(std::time::Duration::from_secs(30), self.state.arrived.notified())
-            .await
-            .expect("data movement multipart operation should reach selected completion");
-    }
-}
-
-#[cfg(test)]
-impl Drop for DataMovementMultipartCompletionBarrier {
-    fn drop(&mut self) {
-        self.state.release.notify_one();
-        let mut slot = DATA_MOVEMENT_MULTIPART_COMPLETION_BARRIER
-            .get_or_init(|| std::sync::Mutex::new(None))
-            .lock()
-            .expect("data movement multipart completion barrier mutex should not poison");
-        if slot.as_ref().is_some_and(|state| Arc::ptr_eq(state, &self.state)) {
-            *slot = None;
-        }
-    }
-}
-
-#[cfg(test)]
-async fn pause_data_movement_multipart_before_selected_completion(bucket: &str) {
-    let barrier = DATA_MOVEMENT_MULTIPART_COMPLETION_BARRIER
-        .get_or_init(|| std::sync::Mutex::new(None))
-        .lock()
-        .expect("data movement multipart completion barrier mutex should not poison")
-        .as_ref()
-        .filter(|barrier| barrier.bucket == bucket)
-        .cloned();
-    if let Some(barrier) = barrier {
-        barrier.arrived.notify_one();
-        barrier.release.notified().await;
-    }
-}
-
 async fn list_pool_multipart_uploads_for_incarnation(
    pool: &crate::core::sets::Sets,
    bucket: &str,
@@ -402,7 +332,7 @@ impl ECStore {
    ) -> Result<MultipartUploadResult> {
        self.handle_new_multipart_upload_with_pool_idx(bucket, object, opts)
            .await
-            .map(|(res, _, _)| res)
+            .map(|(res, _)| res)
    }

    pub(crate) async fn handle_new_multipart_upload_with_pool_idx(
@@ -410,7 +340,7 @@ impl ECStore {
        bucket: &str,
        object: &str,
        opts: &ObjectOptions,
-    ) -> Result<(MultipartUploadResult, usize, Option<Uuid>)> {
+    ) -> Result<(MultipartUploadResult, usize)> {
        check_new_multipart_args(bucket, object)?;
        let (opts, _bucket_lifecycle_guard) = self.guard_multipart_bucket_incarnation(bucket, opts).await?;
        let opts = &opts;
@@ -419,20 +349,7 @@ impl ECStore {
            return self.pools[0]
                .new_multipart_upload(bucket, object, opts)
                .await
-                .map(|res| (res, 0, opts.expected_bucket_incarnation_id));
-        }
-
-        if opts.data_movement && opts.version_id.is_some() {
-            let idx = self.select_data_movement_pool_idx(bucket, object, -1, opts, false).await?;
-            if idx == opts.src_pool_idx {
-                return Err(StorageError::DataMovementOverwriteErr(
-                    bucket.to_owned(),
-                    object.to_owned(),
-                    opts.version_id.clone().unwrap_or_default(),
-                ));
-            }
-            let res = self.pools[idx].new_multipart_upload(bucket, object, opts).await?;
-            return Ok((res, idx, opts.expected_bucket_incarnation_id));
+                .map(|res| (res, 0));
        }

        for (idx, pool) in self.pools.iter().enumerate() {
@@ -455,7 +372,7 @@ impl ECStore {

            if !res.uploads.is_empty() {
                let res = self.pools[idx].new_multipart_upload(bucket, object, opts).await?;
-                return Ok((res, idx, opts.expected_bucket_incarnation_id));
+                return Ok((res, idx));
            }
        }
        let idx = self.get_pool_idx(bucket, object, -1).await?;
@@ -468,7 +385,7 @@ impl ECStore {
        }

        let res = self.pools[idx].new_multipart_upload(bucket, object, opts).await?;
-        Ok((res, idx, opts.expected_bucket_incarnation_id))
+        Ok((res, idx))
    }

    #[instrument(skip(self))]
@@ -539,30 +456,6 @@ impl ECStore {
        Err(StorageError::InvalidUploadID(bucket.to_owned(), object.to_owned(), upload_id.to_owned()))
    }

-    pub(crate) async fn put_object_part_for_data_movement(
-        &self,
-        target_pool_idx: usize,
-        bucket: &str,
-        object: &str,
-        upload_id: &str,
-        data: &mut PutObjReader,
-        opts: &ObjectOptions,
-    ) -> Result<PartInfo> {
-        let part_id = opts
-            .part_number
-            .ok_or_else(|| Error::other("targeted multipart upload requires a part number"))?;
-        check_put_object_part_args(bucket, object, upload_id)?;
-        if !opts.data_movement {
-            return Err(Error::other("targeted multipart upload requires data_movement options"));
-        }
-        let (opts, _bucket_lifecycle_guard) = self.guard_multipart_bucket_incarnation(bucket, opts).await?;
-        let pool = self
-            .pools
-            .get(target_pool_idx)
-            .ok_or_else(|| Error::other(format!("data movement target pool {target_pool_idx} is out of range")))?;
-        pool.put_object_part(bucket, object, upload_id, part_id, data, &opts).await
-    }
-
    #[instrument(skip(self))]
    pub(super) async fn handle_get_multipart_info(
        &self,
@@ -637,26 +530,6 @@ impl ECStore {
        Err(StorageError::InvalidUploadID(bucket.to_owned(), object.to_owned(), upload_id.to_owned()))
    }

-    pub(crate) async fn abort_multipart_upload_for_data_movement(
-        &self,
-        target_pool_idx: usize,
-        bucket: &str,
-        object: &str,
-        upload_id: &str,
-        opts: &ObjectOptions,
-    ) -> Result<()> {
-        check_abort_multipart_args(bucket, object, upload_id)?;
-        if !opts.data_movement {
-            return Err(Error::other("targeted multipart abort requires data_movement options"));
-        }
-        let (opts, _bucket_lifecycle_guard) = self.guard_multipart_bucket_incarnation(bucket, opts).await?;
-        let pool = self
-            .pools
-            .get(target_pool_idx)
-            .ok_or_else(|| Error::other(format!("data movement target pool {target_pool_idx} is out of range")))?;
-        pool.abort_multipart_upload(bucket, object, upload_id, &opts).await
-    }
-
    #[instrument(skip(self))]
    pub(super) async fn handle_complete_multipart_upload(
        self: Arc<Self>,
@@ -701,62 +574,6 @@ impl ECStore {

        Err(StorageError::InvalidUploadID(bucket.to_owned(), object.to_owned(), upload_id.to_owned()))
    }
-
-    pub(crate) async fn complete_multipart_upload_for_data_movement(
-        self: Arc<Self>,
-        target_pool_idx: usize,
-        bucket: &str,
-        object: &str,
-        upload_id: &str,
-        uploaded_parts: Vec<CompletePart>,
-        opts: &ObjectOptions,
-    ) -> Result<ObjectInfo> {
-        check_complete_multipart_args(bucket, object, upload_id)?;
-        if !opts.data_movement {
-            return Err(Error::other("targeted multipart completion requires data_movement options"));
-        }
-        let (mut opts, _bucket_lifecycle_guard) = self.guard_multipart_bucket_incarnation(bucket, opts).await?;
-        if opts.overwrites_existing_version() && !is_meta_bucketname(bucket) {
-            let expected_incarnation_id = opts
-                .expected_bucket_incarnation_id
-                .ok_or_else(|| Error::other("data movement completion is missing its bucket incarnation"))?;
-            let lifecycle_fence = opts
-                .bucket_lifecycle_lock_fence
-                .as_ref()
-                .ok_or_else(|| Error::other("data movement completion is missing its bucket lifecycle fence"))?;
-            let snapshot = match opts.object_lock_config_snapshot.as_ref() {
-                Some(snapshot) => Arc::clone(snapshot),
-                None => {
-                    self.object_lock_config_snapshot_under_lifecycle_fence(bucket, lifecycle_fence)
-                        .await?
-                }
-            };
-            if !snapshot.is_valid_for_destructive_put(self.id, bucket, expected_incarnation_id) {
-                return Err(Error::other(
-                    "data movement Object Lock snapshot does not match the target bucket generation",
-                ));
-            }
-            snapshot.add_lock_fences(&mut opts);
-            opts.object_lock_config_snapshot = Some(snapshot);
-        }
-        #[cfg(test)]
-        pause_data_movement_multipart_before_selected_completion(bucket).await;
-        let pool = self
-            .pools
-            .get(target_pool_idx)
-            .ok_or_else(|| Error::other(format!("data movement target pool {target_pool_idx} is out of range")))?
-            .clone();
-        let result = enqueue_transition_after_write(
-            pool.complete_multipart_upload(bucket, object, upload_id, uploaded_parts, &opts)
-                .await,
-            LcEventSrc::S3CompleteMultipartUpload,
-        )
-        .await;
-        if result.is_ok() {
-            list_objects::observe_list_objects_mutation(self.as_ref(), bucket).await;
-        }
-        result
-    }
 }

 /// Merges per-pool `ListMultipartUploads` pages into a single globally paginated
@@ -667,6 +667,18 @@ impl SelectObjectSnapshotLockLossWake {
    }
 }

+fn select_object_ssec_headers(headers: &HeaderMap) -> HeaderMap {
+    use rustfs_utils::http::headers::{SSEC_ALGORITHM_HEADER, SSEC_KEY_HEADER, SSEC_KEY_MD5_HEADER};
+
+    let mut selected = HeaderMap::new();
+    for name in [SSEC_ALGORITHM_HEADER, SSEC_KEY_HEADER, SSEC_KEY_MD5_HEADER] {
+        if let Some(value) = headers.get(name) {
+            selected.insert(name, value.clone());
+        }
+    }
+    selected
+}
+
 // LockRegistry clones its canonical client Arc for each endpoint host, so an
 // exact Arc set identifies one distributed namespace-lock quorum domain.
 fn same_distributed_lock_domain(left: &[Arc<dyn rustfs_lock::LockClient>], right: &[Arc<dyn rustfs_lock::LockClient>]) -> bool {
@@ -906,7 +918,7 @@ fn is_equivalent_data_movement_delete_marker(source: &ObjectInfo, target: &Objec
        && is_data_movement_delete_marker(target)
        && source.version_id == target.version_id
        && source.mod_time == target.mod_time
-        && is_equivalent_data_movement_delete_marker_metadata(&source.user_defined, &target.user_defined)
+        && source.user_defined == target.user_defined
        && source.user_tags == target.user_tags
        && source.replication_status_internal == target.replication_status_internal
        && source.replication_status == target.replication_status
@@ -914,185 +926,24 @@ fn is_equivalent_data_movement_delete_marker(source: &ObjectInfo, target: &Objec
        && source.version_purge_status == target.version_purge_status
 }

-fn is_equivalent_data_movement_delete_marker_metadata(
-    source: &HashMap<String, String>,
-    target: &HashMap<String, String>,
-) -> bool {
-    matches!(
-        (
-            data_movement_delete_marker_metadata_identity(source),
-            data_movement_delete_marker_metadata_identity(target)
-        ),
-        (Some(source), Some(target)) if source == target
-    )
-}
-
-fn data_movement_delete_marker_metadata_identity(metadata: &HashMap<String, String>) -> Option<HashMap<String, String>> {
-    let mut identity = HashMap::with_capacity(metadata.len());
-    let mut local_tier_free_version_id = None;
-    for (key, value) in metadata {
-        let Some(suffix) = rustfs_utils::http::strip_internal_prefix_preserving_case(key) else {
-            identity.insert(key.clone(), value.clone());
-            continue;
-        };
-
-        if suffix.eq_ignore_ascii_case(rustfs_utils::http::SUFFIX_TIER_FV_ID) {
-            let version_id = Uuid::parse_str(value).ok().filter(|version_id| !version_id.is_nil())?;
-            if local_tier_free_version_id.is_some_and(|expected| expected != version_id) {
-                return None;
-            }
-            local_tier_free_version_id = Some(version_id);
-            continue;
-        }
-
-        let canonical_suffix = [
-            rustfs_utils::http::SUFFIX_REPLICA_TIMESTAMP,
-            rustfs_utils::http::SUFFIX_REPLICA_STATUS,
-            rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP,
-            rustfs_utils::http::SUFFIX_REPLICATION_STATUS,
-            rustfs_utils::http::SUFFIX_PURGESTATUS,
-        ]
-        .into_iter()
-        .find(|candidate| suffix.eq_ignore_ascii_case(candidate))
-        .map(str::to_string)
-        .or_else(|| {
-            [
-                rustfs_utils::http::SUFFIX_REPLICATION_RESET_ARN_PREFIX,
-                rustfs_utils::http::SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX,
-            ]
-            .into_iter()
-            .find_map(|prefix| {
-                suffix
-                    .get(..prefix.len())
-                    .is_some_and(|candidate| candidate.eq_ignore_ascii_case(prefix))
-                    .then(|| format!("{prefix}{}", &suffix[prefix.len()..]))
-            })
-        })
-        .unwrap_or_else(|| suffix.to_string());
-        let canonical_value = if canonical_suffix.eq_ignore_ascii_case(rustfs_utils::http::SUFFIX_REPLICA_TIMESTAMP)
-            || canonical_suffix.eq_ignore_ascii_case(rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP)
-        {
-            rustfs_filemeta::parse_replication_timestamp(value)?
-                .unix_timestamp_nanos()
-                .to_string()
-        } else {
-            value.clone()
-        };
-        let canonical_key = format!("{}{canonical_suffix}", rustfs_utils::http::RUSTFS_INTERNAL_PREFIX);
-        if identity
-            .insert(canonical_key, canonical_value.clone())
-            .is_some_and(|existing| existing != canonical_value)
-        {
-            return None;
-        }
-    }
-    for (status_suffix, timestamp_suffix) in [
-        (rustfs_utils::http::SUFFIX_REPLICA_STATUS, rustfs_utils::http::SUFFIX_REPLICA_TIMESTAMP),
-        (
-            rustfs_utils::http::SUFFIX_REPLICATION_STATUS,
-            rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP,
-        ),
-    ] {
-        let status_key = format!("{}{status_suffix}", rustfs_utils::http::RUSTFS_INTERNAL_PREFIX);
-        let timestamp_key = format!("{}{timestamp_suffix}", rustfs_utils::http::RUSTFS_INTERNAL_PREFIX);
-        match (identity.contains_key(&status_key), identity.contains_key(&timestamp_key)) {
-            (true, false) => {
-                identity.insert(timestamp_key, OffsetDateTime::UNIX_EPOCH.unix_timestamp_nanos().to_string());
-            }
-            (false, true) => return None,
-            _ => {}
-        }
-    }
-    Some(identity)
-}
-
 fn is_data_movement_delete_marker(info: &ObjectInfo) -> bool {
    info.delete_marker
 }

-fn is_expected_data_movement_delete_marker_source(source: &ObjectInfo, expected_mod_time: Option<OffsetDateTime>) -> bool {
-    is_data_movement_delete_marker(source)
-        && source.mod_time.is_some()
-        && source.mod_time == expected_mod_time
-        && data_movement_delete_marker_metadata_identity(&source.user_defined).is_some()
-}
-
-fn current_data_movement_delete_marker_opts(source: &ObjectInfo, opts: &ObjectOptions) -> Option<ObjectOptions> {
-    let replica_status = rustfs_utils::http::get_str(&source.user_defined, rustfs_utils::http::SUFFIX_REPLICA_STATUS);
-    let replica_timestamp = rustfs_utils::http::get_str(&source.user_defined, rustfs_utils::http::SUFFIX_REPLICA_TIMESTAMP);
-    let (replica_status, replica_timestamp) = match (replica_status, replica_timestamp) {
-        (None, None) => Default::default(),
-        (Some(status), timestamp) => {
-            let status = crate::bucket::replication::ReplicationStatusType::from(status.as_str());
-            if status.is_empty() {
-                return None;
-            }
-            let timestamp = match timestamp {
-                Some(timestamp) => rustfs_filemeta::parse_replication_timestamp(&timestamp)?,
-                None => OffsetDateTime::UNIX_EPOCH,
-            };
-            (status, Some(timestamp))
-        }
-        (None, Some(_)) => return None,
-    };
-    let replication_status = rustfs_utils::http::get_str(&source.user_defined, rustfs_utils::http::SUFFIX_REPLICATION_STATUS);
-    let replication_timestamp =
-        rustfs_utils::http::get_str(&source.user_defined, rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP);
-    let (replication_status, replication_timestamp, replication_targets) = match (replication_status, replication_timestamp) {
-        (None, None) => Default::default(),
-        (Some(status), timestamp) => {
-            let direct_status = crate::bucket::replication::ReplicationStatusType::from(status.as_str());
-            let targets = crate::bucket::replication::replication_statuses_map(status.as_str());
-            if direct_status.is_empty() && targets.is_empty() {
-                return None;
-            }
-            let timestamp = match timestamp {
-                Some(timestamp) => rustfs_filemeta::parse_replication_timestamp(&timestamp)?,
-                None => OffsetDateTime::UNIX_EPOCH,
-            };
-            (Some(status), Some(timestamp), targets)
-        }
-        (None, Some(_)) => return None,
-    };
-    let mut state = source.replication_state();
-    if state.target_delete_marker_version_ids_corrupt {
-        return None;
-    }
-    state.replica_status = replica_status;
-    state.replica_timestamp = replica_timestamp;
-    state.replication_status_internal = replication_status;
-    state.replication_timestamp = replication_timestamp;
-    state.targets = replication_targets;
-    state.replicate_decision_str = source.replication_decision.clone();
-    state.delete_marker = true;
-
-    let mut target_opts = opts.clone();
-    target_opts.mod_time = source.mod_time;
-    target_opts.delete_replication = Some(state);
-    Some(target_opts)
-}
-
 fn expected_data_movement_tiered_object(source: &rustfs_filemeta::FileInfo) -> ObjectInfo {
    ObjectInfo::from_file_info(source, "", &source.name, source.version_id.is_some())
 }

 fn is_equivalent_data_movement_tiered_object(source: &rustfs_filemeta::FileInfo, target: &ObjectInfo) -> bool {
    let expected = expected_data_movement_tiered_object(source);
-    let Some(source_actual_size) = effective_object_actual_size(&expected) else {
-        return false;
-    };
-    let Some(target_actual_size) = effective_object_actual_size(target) else {
-        return false;
-    };

    source.version_id == target.version_id
        && !target.delete_marker
        && source.size == target.size
        && source.get_etag() == target.etag
        && source.checksum == target.checksum
-        && crate::data_movement::are_equivalent_data_movement_parts(&source.parts, &target.parts)
        && source.mod_time == target.mod_time
-        && crate::data_movement::is_equivalent_data_movement_metadata(&expected, target, source_actual_size, target_actual_size)
+        && expected.user_defined == target.user_defined
        && expected.user_tags == target.user_tags
        && expected.expires == target.expires
        && expected.storage_class == target.storage_class
@@ -1101,12 +952,11 @@ fn is_equivalent_data_movement_tiered_object(source: &rustfs_filemeta::FileInfo,
        && expected.version_purge_status_internal == target.version_purge_status_internal
        && expected.version_purge_status == target.version_purge_status
        && expected.transitioned_object.status == target.transitioned_object.status
-        && expected.transition_version_state == target.transition_version_state
        && expected.transitioned_object.name == target.transitioned_object.name
        && expected.transitioned_object.tier == target.transitioned_object.tier
        && expected.transitioned_object.version_id == target.transitioned_object.version_id
        && expected.transitioned_object.free_version == target.transitioned_object.free_version
-        && source_actual_size == target_actual_size
+        && effective_object_actual_size(target) == Some(source.size)
 }

 fn should_check_data_movement_resume_target(src_pool_idx: usize, target_pool_idx: usize) -> bool {
@@ -1204,7 +1054,7 @@ impl ECStore {
        )))
    }

-    pub(super) async fn object_lock_config_snapshot_under_lifecycle_fence(
+    async fn object_lock_config_snapshot_under_lifecycle_fence(
        &self,
        bucket: &str,
        lifecycle_fence: &NamespaceLockFence,
@@ -1284,7 +1134,7 @@ impl ECStore {
            pool,
            bucket: bucket.to_owned(),
            object,
-            headers: rustfs_utils::http::project_ssec_transport_headers(headers),
+            headers: select_object_ssec_headers(headers),
            opts,
            object_info,
            logical_size,
@@ -1604,8 +1454,7 @@ impl ECStore {
        target_pool_idx: usize,
        opts: &ObjectOptions,
    ) -> Result<Option<ObjectInfo>> {
-        let mut lookup_opts = version_aware_lookup_opts(opts, true);
-        lookup_opts.include_part_checksums = true;
+        let lookup_opts = version_aware_lookup_opts(opts, true);

        let Some(pool) = self.pools.get(target_pool_idx) else {
            return Err(Error::other(format!(
@@ -1672,25 +1521,6 @@ impl ECStore {
    ) -> Result<()> {
        check_put_object_args(bucket, object)?;

-        let mut opts = opts.clone();
-        let bucket_incarnation_fence = if is_meta_bucketname(bucket) {
-            None
-        } else {
-            let expected = opts
-                .expected_bucket_incarnation_id
-                .ok_or_else(|| Error::other("tiered data movement is missing its bucket incarnation snapshot"))?;
-            let guard = self.acquire_bucket_incarnation_fence(bucket, expected).await?;
-            if let Some(namespace_guard) = guard.namespace_lock_guard() {
-                opts.add_bucket_lifecycle_lock_guard(namespace_guard);
-            }
-            Some(guard)
-        };
-
-        let mut fi = fi.clone();
-        if opts.data_movement {
-            crate::data_movement::prepare_tiered_data_movement_file_info(&mut fi)?;
-        }
-
        let object = encode_dir_object(object);

        if self.single_pool() {
@@ -1703,8 +1533,7 @@ impl ECStore {

        let idx = if opts.data_movement && opts.version_id.is_some() {
            Self::resolve_decommission_target_pool_idx_result(
-                self.select_data_movement_pool_idx(bucket, &object, fi.size, &opts, true)
-                    .await,
+                self.select_data_movement_pool_idx(bucket, &object, fi.size, opts, true).await,
                bucket,
                &object,
            )?
@@ -1721,7 +1550,7 @@ impl ECStore {
                .await;
            let target_pool_idx = resolve_data_movement_resume_target_pool(idx, resume_target_pool_idx, opts.src_pool_idx);
            if self
-                .has_equivalent_data_movement_tiered_object(bucket, &object, &fi, &opts, target_pool_idx)
+                .has_equivalent_data_movement_tiered_object(bucket, &object, fi, opts, target_pool_idx)
                .await?
            {
                return Ok(());
@@ -1734,30 +1563,17 @@ impl ECStore {
            ));
        }

-        let result = self.pools[idx]
-            .get_disks_by_key(&object)
-            .decommission_tiered_object(bucket, &object, &fi, &opts)
-            .await;
-        if matches!(result, Err(Error::PreconditionFailed)) {
-            if self
-                .has_equivalent_data_movement_tiered_object(bucket, &object, &fi, &opts, idx)
-                .await?
-            {
-                return Ok(());
-            }
-            return Err(StorageError::DataMovementOverwriteErr(
-                bucket.to_owned(),
-                object,
-                opts.version_id.clone().unwrap_or_default(),
-            ));
-        }
-        if bucket_incarnation_fence.as_ref().is_some_and(|guard| guard.is_lock_lost()) {
-            return Err(Error::other("tiered data movement bucket incarnation fence was lost during target write"));
-        }
-        Self::resolve_decommission_tiered_object_result(result, bucket, &object)
+        Self::resolve_decommission_tiered_object_result(
+            self.pools[idx]
+                .get_disks_by_key(&object)
+                .decommission_tiered_object(bucket, &object, fi, opts)
+                .await,
+            bucket,
+            &object,
+        )
    }

-    #[instrument(level = "debug", skip(self, h))]
+    #[instrument(level = "debug", skip(self))]
    #[hotpath::measure(impl_type = "ECStore")]
    pub(super) async fn handle_get_object_reader(
        &self,
@@ -1769,7 +1585,7 @@ impl ECStore {
    ) -> Result<GetObjectReader> {
        check_get_obj_args(bucket, object)?;

-        let object = rustfs_utils::path::encode_dir_object_ref(object);
+        let object = encode_dir_object(object);
        let mut opts = opts.clone();
        let read_lock_guard = self
            .acquire_object_read_lock_if_needed("get_object", bucket, &object, &mut opts)
@@ -1777,21 +1593,29 @@ impl ECStore {

        let reader = if self.single_pool() {
            self.pools[0]
-                .get_object_reader(bucket, object.as_ref(), range, h, &opts)
+                .get_object_reader(bucket, object.as_str(), range, h, &opts)
                .await?
        } else {
            let (_, idx) = self
                .get_latest_accessible_object_info_with_idx(bucket, &object, &opts)
                .await?;
            self.pools[idx]
-                .get_object_reader(bucket, object.as_ref(), range, h, &opts)
+                .get_object_reader(bucket, object.as_str(), range, h, &opts)
                .await?
        };

        Ok(Self::attach_read_lock_guard(reader, read_lock_guard))
    }

-    async fn prepare_put_object(&self, bucket: &str, object: &str, opts: &ObjectOptions) -> Result<(String, ObjectOptions)> {
+    #[instrument(level = "debug", skip(self, data))]
+    #[hotpath::measure(impl_type = "ECStore")]
+    pub(super) async fn handle_put_object(
+        &self,
+        bucket: &str,
+        object: &str,
+        data: &mut PutObjReader,
+        opts: &ObjectOptions,
+    ) -> Result<(ObjectInfo, Option<OldCurrentSize>)> {
        check_put_object_args(bucket, object)?;

        let object = encode_dir_object(object);
@@ -1818,20 +1642,22 @@ impl ECStore {
            };
            snapshot.add_lock_fences(&mut opts);
        }
-        Ok((object, opts))
-    }

-    async fn select_put_object_pool_idx(&self, bucket: &str, object: &str, size: i64, opts: &ObjectOptions) -> Result<usize> {
+        // Keep PUT atomic-read friendly: SetDisks takes the object write lock only
+        // around precondition checks and the final rename/commit.
        if self.single_pool() {
-            return Ok(0);
+            return self.pools[0]
+                .put_object_with_old_current_size(bucket, object.as_str(), data, &opts)
+                .await;
        }

        let idx = if opts.data_movement && opts.version_id.is_some() {
-            self.select_data_movement_pool_idx(bucket, object, size, opts, false).await?
+            self.select_data_movement_pool_idx(bucket, &object, data.size(), &opts, false)
+                .await?
        } else if opts.no_lock {
-            self.get_pool_idx_no_lock(bucket, object, size).await?
+            self.get_pool_idx_no_lock(bucket, &object, data.size()).await?
        } else {
-            self.get_pool_idx(bucket, object, size).await?
+            self.get_pool_idx(bucket, &object, data.size()).await?
        };

        if opts.data_movement && idx == opts.src_pool_idx {
@@ -1841,50 +1667,7 @@ impl ECStore {
                opts.version_id.clone().unwrap_or_default(),
            ));
        }
-        Ok(idx)
-    }

-    pub(crate) async fn put_object_for_data_movement(
-        &self,
-        bucket: &str,
-        object: &str,
-        data: &mut PutObjReader,
-        opts: &ObjectOptions,
-    ) -> Result<(usize, Result<ObjectInfo>)> {
-        if !opts.data_movement {
-            return Err(Error::other("data movement PUT requires data_movement options"));
-        }
-        let (object, opts) = self.prepare_put_object(bucket, object, opts).await?;
-        let idx = self
-            .select_put_object_pool_idx(bucket, object.as_str(), data.size(), &opts)
-            .await?;
-        let result = self.pools[idx]
-            .put_object_with_old_current_size(bucket, &object, data, &opts)
-            .await
-            .map(|(object_info, _)| object_info);
-        let result = enqueue_transition_after_write(result, LcEventSrc::S3PutObject).await;
-        if result.is_ok() {
-            list_objects::observe_list_objects_mutation(self, bucket).await;
-        }
-        Ok((idx, result))
-    }
-
-    #[instrument(level = "debug", skip(self, data))]
-    #[hotpath::measure(impl_type = "ECStore")]
-    pub(super) async fn handle_put_object(
-        &self,
-        bucket: &str,
-        object: &str,
-        data: &mut PutObjReader,
-        opts: &ObjectOptions,
-    ) -> Result<(ObjectInfo, Option<OldCurrentSize>)> {
-        let (object, opts) = self.prepare_put_object(bucket, object, opts).await?;
-        let idx = self
-            .select_put_object_pool_idx(bucket, object.as_str(), data.size(), &opts)
-            .await?;
-
-        // Keep PUT atomic-read friendly: SetDisks takes the object write lock only
-        // around precondition checks and the final rename/commit.
        self.pools[idx]
            .put_object_with_old_current_size(bucket, &object, data, &opts)
            .await
@@ -2327,50 +2110,6 @@ impl ECStore {
            };
            let target_pool_idx =
                resolve_data_movement_resume_target_pool(selected_target_pool_idx, resume_target_pool_idx, opts.src_pool_idx);
-            let mut delete_marker_target_opts = None;
-
-            if opts.delete_marker && should_check_data_movement_resume_target(opts.src_pool_idx, target_pool_idx) {
-                let source = self
-                    .find_data_movement_target_info(bucket, object, opts.src_pool_idx, &opts)
-                    .await?;
-                let Some(source) = source else {
-                    return Err(StorageError::DataMovementOverwriteErr(
-                        bucket.to_owned(),
-                        object.to_owned(),
-                        opts.version_id.unwrap_or_default(),
-                    ));
-                };
-                if !is_expected_data_movement_delete_marker_source(&source, opts.mod_time) {
-                    return Err(StorageError::DataMovementOverwriteErr(
-                        bucket.to_owned(),
-                        object.to_owned(),
-                        opts.version_id.unwrap_or_default(),
-                    ));
-                }
-                let Some(target_opts) = current_data_movement_delete_marker_opts(&source, &opts) else {
-                    return Err(StorageError::DataMovementOverwriteErr(
-                        bucket.to_owned(),
-                        object.to_owned(),
-                        opts.version_id.unwrap_or_default(),
-                    ));
-                };
-                let target = self
-                    .find_data_movement_target_info(bucket, object, target_pool_idx, &target_opts)
-                    .await?;
-                if let Some(target) = target {
-                    if is_equivalent_data_movement_delete_marker(&source, &target) {
-                        let mut target = target;
-                        target.name = decode_dir_object(object);
-                        return Ok(target);
-                    }
-                    return Err(StorageError::DataMovementOverwriteErr(
-                        bucket.to_owned(),
-                        object.to_owned(),
-                        opts.version_id.unwrap_or_default(),
-                    ));
-                }
-                delete_marker_target_opts = Some(target_opts);
-            }

            if !should_check_data_movement_resume_target(opts.src_pool_idx, target_pool_idx) {
                if let Ok((source_pool_info, _)) = existing_pool_info
@@ -2398,8 +2137,7 @@ impl ECStore {
                ));
            }

-            let target_opts = delete_marker_target_opts.unwrap_or(opts);
-            let mut obj = self.pools[target_pool_idx].delete_object(bucket, object, target_opts).await?;
+            let mut obj = self.pools[target_pool_idx].delete_object(bucket, object, opts).await?;
            obj.name = decode_dir_object(obj.name.as_str());
            return Ok(obj);
        }
@@ -3348,6 +3086,25 @@ mod tests {
        assert!(second_signal.is_lost());
    }

+    #[test]
+    fn select_snapshot_retains_only_ssec_headers() {
+        use rustfs_utils::http::headers::{SSEC_ALGORITHM_HEADER, SSEC_KEY_HEADER, SSEC_KEY_MD5_HEADER};
+
+        let mut headers = HeaderMap::new();
+        headers.insert(SSEC_ALGORITHM_HEADER, "AES256".parse().expect("valid SSE-C algorithm header"));
+        headers.insert(SSEC_KEY_HEADER, "secret-key".parse().expect("valid SSE-C key header"));
+        headers.insert(SSEC_KEY_MD5_HEADER, "key-md5".parse().expect("valid SSE-C key digest header"));
+        headers.insert("authorization", "credential".parse().expect("valid authorization header"));
+
+        let selected = select_object_ssec_headers(&headers);
+
+        assert_eq!(selected.len(), 3);
+        assert_eq!(selected.get(SSEC_ALGORITHM_HEADER), headers.get(SSEC_ALGORITHM_HEADER));
+        assert_eq!(selected.get(SSEC_KEY_HEADER), headers.get(SSEC_KEY_HEADER));
+        assert_eq!(selected.get(SSEC_KEY_MD5_HEADER), headers.get(SSEC_KEY_MD5_HEADER));
+        assert!(selected.get("authorization").is_none());
+    }
+
    #[test]
    fn tier_delete_entry_is_prepared_and_bound_to_source_generation() {
        let identity = [9_u8; 32];
@@ -3443,247 +3200,6 @@ mod tests {
        assert!(!is_equivalent_data_movement_delete_marker(&source, &mismatched));
    }

-    #[test]
-    fn equivalent_data_movement_delete_marker_accepts_distinct_local_free_version_ids() {
-        let mut source = ObjectInfo {
-            version_id: Some(Uuid::from_u128(1)),
-            delete_marker: true,
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH),
-            ..Default::default()
-        };
-        rustfs_utils::http::insert_str(
-            Arc::make_mut(&mut source.user_defined),
-            rustfs_utils::http::SUFFIX_TIER_FV_ID,
-            Uuid::from_u128(2).to_string(),
-        );
-        let mut target = source.clone();
-        rustfs_utils::http::insert_str(
-            Arc::make_mut(&mut target.user_defined),
-            rustfs_utils::http::SUFFIX_TIER_FV_ID,
-            Uuid::from_u128(3).to_string(),
-        );
-
-        assert!(is_equivalent_data_movement_delete_marker(&source, &target));
-
-        Arc::make_mut(&mut target.user_defined).insert(
-            format!("{}{}", rustfs_utils::http::MINIO_INTERNAL_PREFIX, rustfs_utils::http::SUFFIX_TIER_FV_ID),
-            Uuid::from_u128(4).to_string(),
-        );
-        assert!(!is_equivalent_data_movement_delete_marker(&source, &target));
-    }
-
-    #[test]
-    fn equivalent_data_movement_delete_marker_accepts_replication_alias_expansion() {
-        let key = format!(
-            "{}{}",
-            rustfs_utils::http::MINIO_INTERNAL_PREFIX,
-            rustfs_utils::http::SUFFIX_REPLICATION_STATUS
-        );
-        let timestamp_key = format!(
-            "{}{}",
-            rustfs_utils::http::MINIO_INTERNAL_PREFIX,
-            rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP
-        );
-        let source = ObjectInfo {
-            version_id: Some(Uuid::from_u128(1)),
-            delete_marker: true,
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH),
-            user_defined: Arc::new(HashMap::from([
-                (key.clone(), "arn=COMPLETED;".to_string()),
-                (timestamp_key, "1970-01-01T00:00:01Z".to_string()),
-            ])),
-            ..Default::default()
-        };
-        let mut target = source.clone();
-        rustfs_utils::http::insert_str(
-            Arc::make_mut(&mut target.user_defined),
-            rustfs_utils::http::SUFFIX_REPLICATION_STATUS,
-            "arn=COMPLETED;".to_string(),
-        );
-        rustfs_utils::http::insert_str(
-            Arc::make_mut(&mut target.user_defined),
-            rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP,
-            (OffsetDateTime::UNIX_EPOCH + time::Duration::SECOND).to_string(),
-        );
-        assert!(is_equivalent_data_movement_delete_marker(&source, &target));
-
-        Arc::make_mut(&mut target.user_defined).insert(key, "arn=FAILED;".to_string());
-        assert!(!is_equivalent_data_movement_delete_marker(&source, &target));
-    }
-
-    #[test]
-    fn data_movement_delete_marker_source_requires_persisted_mod_time() {
-        let source = ObjectInfo {
-            delete_marker: true,
-            ..Default::default()
-        };
-        assert!(!is_expected_data_movement_delete_marker_source(&source, None));
-
-        let source = ObjectInfo {
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH),
-            ..source
-        };
-        assert!(is_expected_data_movement_delete_marker_source(&source, Some(OffsetDateTime::UNIX_EPOCH)));
-        assert!(!is_expected_data_movement_delete_marker_source(&source, None));
-    }
-
-    #[test]
-    fn data_movement_delete_marker_uses_current_source_replication_state() {
-        let expected_timestamp = OffsetDateTime::UNIX_EPOCH + time::Duration::SECOND;
-        let timestamp = expected_timestamp.to_string();
-        let mut metadata = HashMap::new();
-        rustfs_utils::http::insert_str(
-            &mut metadata,
-            rustfs_utils::http::SUFFIX_REPLICA_STATUS,
-            ReplicationStatusType::Replica.to_string(),
-        );
-        rustfs_utils::http::insert_str(&mut metadata, rustfs_utils::http::SUFFIX_REPLICA_TIMESTAMP, timestamp.clone());
-        rustfs_utils::http::insert_str(&mut metadata, rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP, timestamp);
-        rustfs_utils::http::insert_str(
-            &mut metadata,
-            rustfs_utils::http::SUFFIX_REPLICATION_STATUS,
-            "arn=COMPLETED;".to_string(),
-        );
-        rustfs_utils::http::insert_str(
-            &mut metadata,
-            &format!(
-                "{}{}",
-                rustfs_utils::http::SUFFIX_REPLICATION_RESET_ARN_PREFIX,
-                "arn:minio:replication::TenantA:bucket"
-            ),
-            "reset-id".to_string(),
-        );
-        rustfs_utils::http::insert_str(
-            &mut metadata,
-            &format!(
-                "{}{}",
-                rustfs_utils::http::SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX,
-                "arn:minio:replication::TenantA:bucket"
-            ),
-            "target-version".to_string(),
-        );
-        let source = ObjectInfo {
-            delete_marker: true,
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH),
-            replication_status_internal: Some("arn=COMPLETED;".to_string()),
-            replication_decision: "arn=replicate;".to_string(),
-            user_defined: Arc::new(metadata),
-            ..Default::default()
-        };
-        let opts = ObjectOptions {
-            mod_time: source.mod_time,
-            delete_replication: Some(ReplicationState {
-                replication_status_internal: Some("arn=PENDING;".to_string()),
-                ..Default::default()
-            }),
-            ..Default::default()
-        };
-
-        let target_opts = current_data_movement_delete_marker_opts(&source, &opts).expect("valid current source state");
-        let state = target_opts.delete_replication.as_ref().expect("current replication state");
-        assert_eq!(state.replication_status_internal.as_deref(), Some("arn=COMPLETED;"));
-        assert_eq!(state.replica_status, crate::bucket::replication::ReplicationStatusType::Replica);
-        assert_eq!(state.replica_timestamp, Some(expected_timestamp));
-        assert_eq!(state.replication_timestamp, state.replica_timestamp);
-        assert_eq!(state.replicate_decision_str, "arn=replicate;");
-        assert_eq!(
-            state
-                .reset_statuses_map
-                .get("arn:minio:replication::TenantA:bucket")
-                .map(String::as_str),
-            Some("reset-id")
-        );
-        assert_eq!(
-            state
-                .target_delete_marker_version_ids
-                .get("arn:minio:replication::TenantA:bucket")
-                .map(String::as_str),
-            Some("target-version")
-        );
-    }
-
-    #[test]
-    fn data_movement_delete_marker_rejects_corrupt_target_version_maps() {
-        let suffix = format!("{}not-an-arn", rustfs_utils::http::SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX);
-        let mut malformed = HashMap::new();
-        rustfs_utils::http::insert_str(&mut malformed, &suffix, "target-version".to_string());
-        let malformed_source = ObjectInfo {
-            delete_marker: true,
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH),
-            user_defined: Arc::new(malformed),
-            ..Default::default()
-        };
-        assert!(current_data_movement_delete_marker_opts(&malformed_source, &ObjectOptions::default()).is_none());
-
-        let mut conflicted = HashMap::new();
-        let suffix = format!(
-            "{}arn:minio:replication::target:bucket",
-            rustfs_utils::http::SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX
-        );
-        rustfs_utils::http::insert_str(&mut conflicted, &suffix, "target-version-a".to_string());
-        conflicted.insert(
-            format!("{}{suffix}", rustfs_utils::http::MINIO_INTERNAL_PREFIX),
-            "target-version-b".to_string(),
-        );
-        let conflicted_source = ObjectInfo {
-            user_defined: Arc::new(conflicted),
-            ..malformed_source.clone()
-        };
-        assert!(current_data_movement_delete_marker_opts(&conflicted_source, &ObjectOptions::default()).is_none());
-
-        let mut over_cap = HashMap::new();
-        for index in 0..=1_000 {
-            let suffix = format!(
-                "{}arn:minio:replication::target:bucket-{index}",
-                rustfs_utils::http::SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX
-            );
-            rustfs_utils::http::insert_str(&mut over_cap, &suffix, format!("target-version-{index}"));
-        }
-        let over_cap_source = ObjectInfo {
-            user_defined: Arc::new(over_cap),
-            ..malformed_source
-        };
-        assert!(current_data_movement_delete_marker_opts(&over_cap_source, &ObjectOptions::default()).is_none());
-    }
-
-    #[test]
-    fn data_movement_delete_marker_normalizes_legacy_missing_replication_timestamps() {
-        let mut source_metadata = HashMap::new();
-        rustfs_utils::http::insert_str(
-            &mut source_metadata,
-            rustfs_utils::http::SUFFIX_REPLICA_STATUS,
-            ReplicationStatusType::Replica.to_string(),
-        );
-        rustfs_utils::http::insert_str(
-            &mut source_metadata,
-            rustfs_utils::http::SUFFIX_REPLICATION_STATUS,
-            "arn=COMPLETED;".to_string(),
-        );
-        let source = ObjectInfo {
-            delete_marker: true,
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH),
-            replication_status_internal: Some("arn=COMPLETED;".to_string()),
-            user_defined: Arc::new(source_metadata),
-            ..Default::default()
-        };
-
-        let target_opts = current_data_movement_delete_marker_opts(&source, &ObjectOptions::default())
-            .expect("legacy status-only metadata should remain migratable");
-        let state = target_opts
-            .delete_replication
-            .expect("replication state should be reconstructed");
-        assert_eq!(state.replica_timestamp, Some(OffsetDateTime::UNIX_EPOCH));
-        assert_eq!(state.replication_timestamp, Some(OffsetDateTime::UNIX_EPOCH));
-
-        let mut target_metadata = (*source.user_defined).clone();
-        let epoch = OffsetDateTime::UNIX_EPOCH
-            .format(&time::format_description::well_known::Rfc3339)
-            .unwrap();
-        rustfs_utils::http::insert_str(&mut target_metadata, rustfs_utils::http::SUFFIX_REPLICA_TIMESTAMP, epoch.clone());
-        rustfs_utils::http::insert_str(&mut target_metadata, rustfs_utils::http::SUFFIX_REPLICATION_TIMESTAMP, epoch);
-        assert!(is_equivalent_data_movement_delete_marker_metadata(&source.user_defined, &target_metadata));
-    }
-
    #[test]
    fn equivalent_data_movement_delete_marker_rejects_metadata_and_replication_mismatch() {
        let version_id = Uuid::nil();
@@ -3828,67 +3344,6 @@ mod tests {
        assert!(is_equivalent_data_movement_tiered_object(&source, &target));
    }

-    #[test]
-    fn equivalent_data_movement_tiered_object_uses_logical_compressed_and_encrypted_sizes() {
-        let mut compressed = tiered_equivalence_source();
-        compressed.size = 600;
-        rustfs_utils::http::insert_str(&mut compressed.metadata, rustfs_utils::http::SUFFIX_COMPRESSION, "S2".to_string());
-        rustfs_utils::http::insert_str(&mut compressed.metadata, rustfs_utils::http::SUFFIX_ACTUAL_SIZE, "1024".to_string());
-        let compressed_target = tiered_equivalence_target(&compressed);
-        assert!(is_equivalent_data_movement_tiered_object(&compressed, &compressed_target));
-
-        let mut encrypted = tiered_equivalence_source();
-        encrypted.size = 640;
-        encrypted.metadata.insert(
-            rustfs_utils::http::object_encryption_keys::INTERNAL_ENCRYPTION_KEY_ID_HEADER.to_string(),
-            "key-id".to_string(),
-        );
-        encrypted.metadata.insert(
-            rustfs_utils::http::object_encryption_keys::INTERNAL_ENCRYPTION_ORIGINAL_SIZE_HEADER.to_string(),
-            "1024".to_string(),
-        );
-        let encrypted_target = tiered_equivalence_target(&encrypted);
-        assert!(is_equivalent_data_movement_tiered_object(&encrypted, &encrypted_target));
-    }
-
-    #[test]
-    fn equivalent_data_movement_tiered_object_accepts_transition_alias_expansion() {
-        let mut source = tiered_equivalence_source();
-        let suffix = rustfs_utils::http::SUFFIX_TRANSITION_TIER;
-        source.metadata.insert(
-            format!("{}{suffix}", rustfs_utils::http::MINIO_INTERNAL_PREFIX),
-            source.transition_tier.clone(),
-        );
-        let mut target = tiered_equivalence_target(&source);
-        Arc::make_mut(&mut target.user_defined)
-            .insert(rustfs_utils::http::internal_key_rustfs(suffix), source.transition_tier.clone());
-
-        assert!(is_equivalent_data_movement_tiered_object(&source, &target));
-    }
-
-    #[test]
-    fn equivalent_data_movement_tiered_object_requires_hydrated_part_checksums() {
-        let mut source = tiered_equivalence_source();
-        source.parts = vec![rustfs_filemeta::ObjectPartInfo {
-            number: 1,
-            mod_time: Some(OffsetDateTime::UNIX_EPOCH + time::Duration::SECOND),
-            checksums: Some(HashMap::from([("CRC32C".to_string(), "AAAAAA==".to_string())])),
-            ..Default::default()
-        }];
-        rustfs_utils::http::insert_str(
-            &mut source.metadata,
-            rustfs_utils::http::SUFFIX_PART_CHECKSUMS,
-            r#"[[1,[["CRC32C","AAAAAA=="]]]]"#.to_string(),
-        );
-        let mut target = tiered_equivalence_target(&source);
-        Arc::make_mut(&mut target.parts)[0].mod_time = None;
-        assert!(is_equivalent_data_movement_tiered_object(&source, &target));
-
-        let mut missing = target;
-        Arc::make_mut(&mut missing.parts)[0].checksums = None;
-        assert!(!is_equivalent_data_movement_tiered_object(&source, &missing));
-    }
-
    #[test]
    fn equivalent_data_movement_tiered_object_rejects_transition_mismatch() {
        let source = tiered_equivalence_source();
@@ -3898,16 +3353,6 @@ mod tests {
        assert!(!is_equivalent_data_movement_tiered_object(&source, &target));
    }

-    #[test]
-    fn equivalent_data_movement_tiered_object_rejects_transition_version_state_mismatch() {
-        let mut source = tiered_equivalence_source();
-        source.transition_version_state = rustfs_filemeta::TransitionVersionState::Exact;
-        let mut target = tiered_equivalence_target(&source);
-        target.transition_version_state = rustfs_filemeta::TransitionVersionState::Unknown;
-
-        assert!(!is_equivalent_data_movement_tiered_object(&source, &target));
-    }
-
    #[test]
    fn equivalent_data_movement_tiered_object_rejects_user_metadata_mismatch() {
        let source = tiered_equivalence_source();
@@ -4577,8 +4022,6 @@ mod tests {
            assert_eq!(snapshot.headers.get(SSEC_KEY_HEADER), request_headers.get(SSEC_KEY_HEADER));
            assert_eq!(snapshot.headers.get(SSEC_KEY_MD5_HEADER), request_headers.get(SSEC_KEY_MD5_HEADER));
            assert!(snapshot.headers.get("authorization").is_none());
-            assert!(snapshot.headers.values().all(http::HeaderValue::is_sensitive));
-            assert!(!format!("{:?}", snapshot.headers).contains("secret-key"));
            assert_eq!(
                snapshot.logical_size(),
                u64::try_from(payload.len()).expect("test payload length should fit in u64")
@@ -109,7 +109,6 @@ async fn run_legacy_bitrot_test_for_object(root: &std::path::Path, disk_name: &s
        FileInfoOpts {
            data: true, // need inline data for inline objects
            include_free_versions: false,
-            include_part_checksums: true,
        },
    ) {
        Ok(f) => f,
@@ -37,7 +37,6 @@ crc-fast = { workspace = true }
 rmp.workspace = true
 rmp-serde.workspace = true
 serde = { workspace = true, features = ["derive"] }
-serde_json.workspace = true
 time = { workspace = true, features = ["parsing", "formatting", "macros", "serde"] }
 uuid = { workspace = true, features = ["v4", "fast-rng", "serde", "macro-diagnostics"] }
 tokio = { workspace = true, features = ["io-util", "macros", "sync", "fs", "rt-multi-thread"] }
@@ -55,6 +54,7 @@ arc-swap.workspace = true
 criterion = { workspace = true, features = ["html_reports"] }
 tempfile = { workspace = true }
 proptest = "1"
+serde_json.workspace = true

 [[bench]]
 name = "xl_meta_bench"
@@ -52,7 +52,6 @@ fn main() {
        FileInfoOpts {
            data: false,
            include_free_versions: true,
-            include_part_checksums: true,
        },
    )
    .expect("decode file info");
@@ -17,9 +17,9 @@ use bytes::Bytes;
 use rmp_serde::Serializer;
 use rustfs_utils::HashAlgorithm;
 use rustfs_utils::http::{
-    AMZ_OBJECT_TAGGING, SUFFIX_COMPRESSION, SUFFIX_DATA_MOVED, SUFFIX_DATA_MOVED_TAGS, SUFFIX_FREE_VERSION, SUFFIX_HEALING,
-    SUFFIX_INLINE_DATA, SUFFIX_TIER_FV_ID, SUFFIX_TIER_FV_MARKER, SUFFIX_TIER_SKIP_FV_ID, contains_key_str, get_str,
-    has_internal_suffix, insert_str, is_encryption_metadata_key, starts_with_ignore_ascii_case,
+    SUFFIX_COMPRESSION, SUFFIX_DATA_MOVED, SUFFIX_FREE_VERSION, SUFFIX_HEALING, SUFFIX_INLINE_DATA, SUFFIX_TIER_FV_ID,
+    SUFFIX_TIER_FV_MARKER, SUFFIX_TIER_SKIP_FV_ID, contains_key_str, get_str, has_internal_suffix, insert_str,
+    is_encryption_metadata_key, starts_with_ignore_ascii_case,
 };
 use s3s::dto::{RestoreStatus, Timestamp};
 use s3s::header::X_AMZ_RESTORE;
@@ -232,17 +232,6 @@ pub enum TransitionVersionState {
    Exact,
 }

-impl TransitionVersionState {
-    pub const fn as_str(self) -> &'static str {
-        match self {
-            Self::Unknown => "unknown",
-            Self::KnownDisabled => "known-disabled",
-            Self::SuspendedNull => "suspended-null",
-            Self::Exact => "exact",
-        }
-    }
-}
-
 #[derive(PartialEq, Clone, Default)]
 pub struct FileInfo {
    pub volume: String,
@@ -1162,16 +1151,9 @@ impl FileInfo {
    }

    pub fn set_data_moved(&mut self) {
-        let tags_proof = format!("v1:{}", self.metadata.get(AMZ_OBJECT_TAGGING).map(String::as_str).unwrap_or_default());
-        insert_str(&mut self.metadata, SUFFIX_DATA_MOVED_TAGS, tags_proof);
        insert_str(&mut self.metadata, SUFFIX_DATA_MOVED, "true".to_string());
    }

-    pub fn acknowledge_data_movement(&mut self) {
-        // Keep both empty aliases so mixed-version disks retain one metadata identity.
-        insert_str(&mut self.metadata, SUFFIX_DATA_MOVED, String::new());
-    }
-
    pub fn inline_data(&self) -> bool {
        contains_key_str(&self.metadata, SUFFIX_INLINE_DATA) && !self.is_remote()
    }
@@ -206,42 +206,6 @@ fn persist_reset_statuses(meta_sys: &mut HashMap<String, Vec<u8>>, reset_statuse
    }
 }

-pub fn parse_replication_timestamp(value: &str) -> Option<OffsetDateTime> {
-    const DISPLAY_FORMAT: &[time::format_description::BorrowedFormatItem<'_>] = time::macros::format_description!(
-        "[year sign:automatic]-[month]-[day] [hour padding:none]:[minute]:[second].[subsecond] [offset_hour sign:mandatory]:[offset_minute]:[offset_second]"
-    );
-    OffsetDateTime::parse(value, &Rfc3339)
-        .or_else(|_| OffsetDateTime::parse(value, DISPLAY_FORMAT))
-        .ok()
-}
-
-fn format_replication_timestamp(value: Option<OffsetDateTime>) -> String {
-    let value = value.unwrap_or(OffsetDateTime::UNIX_EPOCH);
-    value
-        .to_offset(time::UtcOffset::UTC)
-        .format(&Rfc3339)
-        .unwrap_or_else(|_| value.to_string())
-}
-
-fn persist_delete_marker_replication_state(meta_sys: &mut HashMap<String, Vec<u8>>, state: &ReplicationState) {
-    if !state.replica_status.is_empty() {
-        insert_bytes(meta_sys, SUFFIX_REPLICA_STATUS, state.replica_status.as_str().as_bytes().to_vec());
-        insert_bytes(
-            meta_sys,
-            SUFFIX_REPLICA_TIMESTAMP,
-            format_replication_timestamp(state.replica_timestamp).into_bytes(),
-        );
-    }
-    if let Some(status) = state.replication_status_internal.as_ref().filter(|status| !status.is_empty()) {
-        insert_bytes(meta_sys, SUFFIX_REPLICATION_STATUS, status.as_bytes().to_vec());
-        insert_bytes(
-            meta_sys,
-            SUFFIX_REPLICATION_TIMESTAMP,
-            format_replication_timestamp(state.replication_timestamp).into_bytes(),
-        );
-    }
-}
-
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
 pub struct FileMeta {
    pub versions: Vec<FileMetaShallowVersion>,
@@ -249,13 +213,6 @@ pub struct FileMeta {
    pub meta_ver: u8,
 }

-struct FileInfoDecodeOptions {
-    read_data: bool,
-    include_free_versions: bool,
-    all_parts: bool,
-    include_part_checksums: bool,
-}
-
 impl FileMeta {
    pub fn new() -> Self {
        Self {
@@ -554,8 +511,53 @@ impl FileMeta {
        }

        if fi.deleted {
-            if let (Some(delete_marker), Some(state)) = (ventry.delete_marker.as_mut(), fi.replication_state_internal.as_ref()) {
-                persist_delete_marker_replication_state(&mut delete_marker.meta_sys, state);
+            if !fi.delete_marker_replication_status().is_empty()
+                && let Some(delete_marker) = ventry.delete_marker.as_mut()
+            {
+                if fi.delete_marker_replication_status() == ReplicationStatusType::Replica {
+                    insert_bytes(
+                        &mut delete_marker.meta_sys,
+                        SUFFIX_REPLICA_STATUS,
+                        fi.replication_state_internal
+                            .as_ref()
+                            .map(|v| v.replica_status.clone())
+                            .unwrap_or_default()
+                            .as_str()
+                            .as_bytes()
+                            .to_vec(),
+                    );
+                    insert_bytes(
+                        &mut delete_marker.meta_sys,
+                        SUFFIX_REPLICA_TIMESTAMP,
+                        fi.replication_state_internal
+                            .as_ref()
+                            .map(|v| v.replica_timestamp.unwrap_or(OffsetDateTime::UNIX_EPOCH).to_string())
+                            .unwrap_or_default()
+                            .as_bytes()
+                            .to_vec(),
+                    );
+                } else {
+                    insert_bytes(
+                        &mut delete_marker.meta_sys,
+                        SUFFIX_REPLICATION_STATUS,
+                        fi.replication_state_internal
+                            .as_ref()
+                            .map(|v| v.replication_status_internal.clone().unwrap_or_default())
+                            .unwrap_or_default()
+                            .as_bytes()
+                            .to_vec(),
+                    );
+                    insert_bytes(
+                        &mut delete_marker.meta_sys,
+                        SUFFIX_REPLICATION_TIMESTAMP,
+                        fi.replication_state_internal
+                            .as_ref()
+                            .map(|v| v.replication_timestamp.unwrap_or(OffsetDateTime::UNIX_EPOCH).to_string())
+                            .unwrap_or_default()
+                            .as_bytes()
+                            .to_vec(),
+                    );
+                }
            }

            if !fi.version_purge_status().is_empty()
@@ -607,8 +609,51 @@ impl FileMeta {
                        }

                        if let Some(delete_marker) = v.delete_marker.as_mut() {
-                            if let Some(state) = fi.replication_state_internal.as_ref() {
-                                persist_delete_marker_replication_state(&mut delete_marker.meta_sys, state);
+                            if !fi.delete_marker_replication_status().is_empty() {
+                                if fi.delete_marker_replication_status() == ReplicationStatusType::Replica {
+                                    insert_bytes(
+                                        &mut delete_marker.meta_sys,
+                                        SUFFIX_REPLICA_STATUS,
+                                        fi.replication_state_internal
+                                            .as_ref()
+                                            .map(|v| v.replica_status.clone())
+                                            .unwrap_or_default()
+                                            .as_str()
+                                            .as_bytes()
+                                            .to_vec(),
+                                    );
+                                    insert_bytes(
+                                        &mut delete_marker.meta_sys,
+                                        SUFFIX_REPLICA_TIMESTAMP,
+                                        fi.replication_state_internal
+                                            .as_ref()
+                                            .map(|v| v.replica_timestamp.unwrap_or(OffsetDateTime::UNIX_EPOCH).to_string())
+                                            .unwrap_or_default()
+                                            .as_bytes()
+                                            .to_vec(),
+                                    );
+                                } else {
+                                    insert_bytes(
+                                        &mut delete_marker.meta_sys,
+                                        SUFFIX_REPLICATION_STATUS,
+                                        fi.replication_state_internal
+                                            .as_ref()
+                                            .map(|v| v.replication_status_internal.clone().unwrap_or_default())
+                                            .unwrap_or_default()
+                                            .as_bytes()
+                                            .to_vec(),
+                                    );
+                                    insert_bytes(
+                                        &mut delete_marker.meta_sys,
+                                        SUFFIX_REPLICATION_TIMESTAMP,
+                                        fi.replication_state_internal
+                                            .as_ref()
+                                            .map(|v| v.replication_timestamp.unwrap_or(OffsetDateTime::UNIX_EPOCH).to_string())
+                                            .unwrap_or_default()
+                                            .as_bytes()
+                                            .to_vec(),
+                                    );
+                                }
                            }

                            if let Some(state) = fi.replication_state_internal.as_ref() {
@@ -728,47 +773,6 @@ impl FileMeta {
        read_data: bool,
        include_free_versions: bool,
        all_parts: bool,
-    ) -> Result<FileInfo> {
-        self.to_fileinfo_with_part_checksums(
-            volume,
-            path,
-            version_id,
-            FileInfoDecodeOptions {
-                read_data,
-                include_free_versions,
-                all_parts,
-                include_part_checksums: true,
-            },
-        )
-    }
-
-    pub fn into_fileinfo_without_part_checksums(
-        &self,
-        volume: &str,
-        path: &str,
-        version_id: &str,
-        read_data: bool,
-        include_free_versions: bool,
-    ) -> Result<FileInfo> {
-        self.to_fileinfo_with_part_checksums(
-            volume,
-            path,
-            version_id,
-            FileInfoDecodeOptions {
-                read_data,
-                include_free_versions,
-                all_parts: true,
-                include_part_checksums: false,
-            },
-        )
-    }
-
-    fn to_fileinfo_with_part_checksums(
-        &self,
-        volume: &str,
-        path: &str,
-        version_id: &str,
-        opts: FileInfoDecodeOptions,
    ) -> Result<FileInfo> {
        let vid = {
            if !version_id.is_empty() {
@@ -791,7 +795,7 @@ impl FileMeta {

            if header.free_version() {
                non_free_versions -= 1;
-                if opts.include_free_versions
+                if include_free_versions
                    && found_free_version.is_none()
                    && let Ok(found_free_fi) = ver.parse_version_meta()
                    && found_free_fi.version_type != VersionType::Invalid
@@ -802,8 +806,7 @@ impl FileMeta {
                    // Known side effect: if a disk holds only free versions and they are
                    // corrupt, `into_fileinfo` falls through to `FileNotFound` (not
                    // `FileCorrupt`), so that disk is not enqueued for heal.
-                    match found_free_fi.to_fileinfo_with_part_checksums(volume, path, opts.all_parts, opts.include_part_checksums)
-                    {
+                    match found_free_fi.into_fileinfo(volume, path, all_parts) {
                        Ok(mut free_fi) => {
                            free_fi.is_latest = true;
                            found_free_version = Some(free_fi);
@@ -831,14 +834,14 @@ impl FileMeta {

            found = true;

-            let mut fi = ver.to_fileinfo_with_part_checksums(volume, path, opts.all_parts, opts.include_part_checksums)?;
+            let mut fi = ver.into_fileinfo(volume, path, all_parts)?;
            fi.is_latest = is_latest;

            if let Some(_d) = succ_mod_time {
                fi.successor_mod_time = succ_mod_time;
            }

-            if opts.read_data && fi.inline_data() {
+            if read_data && fi.inline_data() {
                fi.data = self.find_inline_data_for_version(fi.version_id)?.map(bytes::Bytes::from);
            }

@@ -847,7 +850,7 @@ impl FileMeta {

        if !found {
            if version_id.is_empty() {
-                if opts.include_free_versions
+                if include_free_versions
                    && non_free_versions == 0
                    && let Some(free_version) = found_free_version
                {
@@ -1534,68 +1537,6 @@ mod test {
        assert_eq!(meta_sys2.len(), 2, "must not create a double-prefixed key");
    }

-    #[test]
-    fn persist_delete_marker_replication_state_keeps_replica_and_target_statuses() {
-        let replica_timestamp = OffsetDateTime::UNIX_EPOCH + time::Duration::SECOND;
-        let replication_timestamp = replica_timestamp + time::Duration::SECOND;
-        let state = ReplicationState {
-            replica_status: ReplicationStatusType::Replica,
-            replica_timestamp: Some(replica_timestamp),
-            replication_status_internal: Some("arn:target=COMPLETED;".to_string()),
-            replication_timestamp: Some(replication_timestamp),
-            ..Default::default()
-        };
-        let mut meta_sys = HashMap::new();
-        let replica_timestamp_string = replica_timestamp
-            .format(&Rfc3339)
-            .expect("timestamp should format as RFC3339");
-        let replication_timestamp_string = replication_timestamp
-            .format(&Rfc3339)
-            .expect("timestamp should format as RFC3339");
-
-        persist_delete_marker_replication_state(&mut meta_sys, &state);
-
-        assert_eq!(
-            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICA_STATUS).as_deref(),
-            Some(b"REPLICA".as_slice())
-        );
-        assert_eq!(
-            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICA_TIMESTAMP).as_deref(),
-            Some(replica_timestamp_string.as_bytes())
-        );
-        assert_eq!(
-            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICATION_STATUS).as_deref(),
-            Some(b"arn:target=COMPLETED;".as_slice())
-        );
-        assert_eq!(
-            rustfs_utils::http::get_bytes(&meta_sys, SUFFIX_REPLICATION_TIMESTAMP).as_deref(),
-            Some(replication_timestamp_string.as_bytes())
-        );
-    }
-
-    #[test]
-    fn persist_delete_marker_replication_timestamp_normalizes_second_offset_to_utc() {
-        let timestamp = OffsetDateTime::UNIX_EPOCH.to_offset(time::UtcOffset::from_hms(5, 30, 15).expect("valid offset"));
-        assert_eq!(parse_replication_timestamp(&timestamp.to_string()), Some(timestamp));
-        let state = ReplicationState {
-            replica_status: ReplicationStatusType::Replica,
-            replica_timestamp: Some(timestamp),
-            replication_status_internal: Some("arn:target=COMPLETED;".to_string()),
-            replication_timestamp: Some(timestamp),
-            ..Default::default()
-        };
-        let mut meta_sys = HashMap::new();
-
-        persist_delete_marker_replication_state(&mut meta_sys, &state);
-
-        for suffix in [SUFFIX_REPLICA_TIMESTAMP, SUFFIX_REPLICATION_TIMESTAMP] {
-            let persisted = rustfs_utils::http::get_bytes(&meta_sys, suffix).expect("timestamp must be persisted");
-            let persisted = std::str::from_utf8(&persisted).expect("timestamp must be UTF-8");
-            assert_eq!(parse_replication_timestamp(persisted), Some(timestamp));
-            assert_ne!(persisted, OffsetDateTime::UNIX_EPOCH.to_string());
-        }
-    }
-
    /// Regression test for rustfs/rustfs#2715: a corrupted version count in
    /// xl.meta must yield a decode error instead of sizing a huge allocation
    /// from the bogus count (which aborts the whole process).
@@ -29,12 +29,11 @@ use super::*;
 use crate::{ChecksumInfo, TransitionVersionState};
 use rustfs_utils::HashAlgorithm;
 use rustfs_utils::http::{
-    RUSTFS_INTERNAL_PREFIX, SUFFIX_CRC, SUFFIX_FREE_VERSION, SUFFIX_INLINE_DATA, SUFFIX_PART_CHECKSUMS, SUFFIX_PURGESTATUS,
-    SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX, SUFFIX_REPLICATION_RESET_ARN_PREFIX, SUFFIX_TIER_FV_ID,
+    RUSTFS_INTERNAL_PREFIX, SUFFIX_CRC, SUFFIX_FREE_VERSION, SUFFIX_INLINE_DATA, SUFFIX_PURGESTATUS, SUFFIX_TIER_FV_ID,
    SUFFIX_TIER_FV_MARKER, SUFFIX_TRANSITION_STATUS, SUFFIX_TRANSITION_TIER, SUFFIX_TRANSITION_TIER_DESTINATION_ID,
    SUFFIX_TRANSITIONED_OBJECTNAME, SUFFIX_TRANSITIONED_VERSION_ID, SUFFIX_TRANSITIONED_VERSION_STATE, contains_key_bytes,
    get_bytes, get_consistent_bytes, get_str, has_internal_suffix, insert_bytes, is_internal_key, remove_bytes,
-    strip_internal_prefix, strip_internal_prefix_preserving_case, target_delete_marker_versions,
+    strip_internal_prefix, target_delete_marker_versions,
 };

 const MSGPACK_EXT8: u8 = 0xc7;
@@ -259,181 +258,63 @@ fn parse_legacy_uuid_bytes(bytes: &[u8], field: &str) -> Result<Option<Uuid>> {
 /// Legacy RustFS writes used 16 raw UUID bytes. New writes and MinIO-migrated
 /// records use the provider's exact UTF-8 version text. Empty, nil UUID, and
 /// malformed bytes are not usable remote versions.
-fn transition_version_state_from_bytes(value: Option<&[u8]>) -> Result<TransitionVersionState> {
-    let Some(value) = value else {
-        return Ok(TransitionVersionState::Unknown);
+fn transitioned_version_from_meta_sys(meta_sys: &HashMap<String, Vec<u8>>) -> Result<Option<String>> {
+    if !contains_key_bytes(meta_sys, SUFFIX_TRANSITIONED_VERSION_ID) {
+        return Ok(None);
+    }
+    let Some(value) = get_consistent_bytes(meta_sys, SUFFIX_TRANSITIONED_VERSION_ID) else {
+        return Ok(None);
    };
-    match value {
-        b"known-disabled" => Ok(TransitionVersionState::KnownDisabled),
-        b"suspended-null" => Ok(TransitionVersionState::SuspendedNull),
-        b"exact" => Ok(TransitionVersionState::Exact),
-        b"unknown" => Ok(TransitionVersionState::Unknown),
-        _ => Err(Error::FileCorrupt),
-    }
-}
-
-fn transitioned_version_from_bytes(value: Option<&[u8]>, state: TransitionVersionState) -> Option<String> {
-    let value = value?;
+    let value = value.to_vec();
    if value.is_empty() {
-        return None;
+        return Ok(None);
    }
-    if state == TransitionVersionState::Unknown
-        && let Ok(id) = Uuid::from_slice(value)
-    {
-        return (!id.is_nil()).then(|| id.to_string());
+    if let Ok(id) = Uuid::from_slice(&value) {
+        return Ok((!id.is_nil()).then(|| id.to_string()));
    }
-    let Ok(value) = std::str::from_utf8(value) else {
-        return None;
+    let Ok(value) = String::from_utf8(value) else {
+        return Ok(None);
    };
    if value.is_empty()
        || value.len() > MAX_TRANSITION_VERSION_LEN
        || value.chars().any(char::is_control)
-        || Uuid::parse_str(value).is_ok_and(|id| id.is_nil())
+        || Uuid::parse_str(&value).is_ok_and(|id| id.is_nil())
    {
-        None
+        Ok(None)
    } else {
-        Some(value.to_string())
+        Ok(Some(value))
    }
 }

-fn validate_transition_version_state(state: TransitionVersionState, version: Option<&str>) -> Result<()> {
+fn transition_version_state_from_meta_sys(
+    meta_sys: &HashMap<String, Vec<u8>>,
+    version: Option<&str>,
+) -> Result<TransitionVersionState> {
+    if !contains_key_bytes(meta_sys, SUFFIX_TRANSITIONED_VERSION_STATE) {
+        return Ok(TransitionVersionState::Unknown);
+    }
+    let value = get_consistent_bytes(meta_sys, SUFFIX_TRANSITIONED_VERSION_STATE).ok_or(Error::FileCorrupt)?;
+    let state = match value {
+        b"known-disabled" => TransitionVersionState::KnownDisabled,
+        b"suspended-null" => TransitionVersionState::SuspendedNull,
+        b"exact" => TransitionVersionState::Exact,
+        b"unknown" => TransitionVersionState::Unknown,
+        _ => return Err(Error::FileCorrupt),
+    };
    let valid = match state {
        TransitionVersionState::Unknown | TransitionVersionState::KnownDisabled => version.is_none(),
        TransitionVersionState::SuspendedNull => version == Some("null"),
        TransitionVersionState::Exact => version.is_some_and(|value| value != "null"),
    };
-    valid.then_some(()).ok_or(Error::FileCorrupt)
+    valid.then_some(state).ok_or(Error::FileCorrupt)
 }

-#[derive(Default)]
-struct DerivedInternalMetadata<'a> {
-    checksum: Option<&'a [u8]>,
-    part_checksums: Option<&'a [u8]>,
-    transition_status: Option<&'a [u8]>,
-    transitioned_object: Option<&'a [u8]>,
-    transitioned_version: Option<&'a [u8]>,
-    transitioned_version_state: Option<&'a [u8]>,
-    transition_tier: Option<&'a [u8]>,
-}
-
-impl<'a> DerivedInternalMetadata<'a> {
-    fn from_meta_sys(meta_sys: &'a HashMap<String, Vec<u8>>) -> Result<Self> {
-        let mut canonical = Self::default();
-        let mut legacy = Self::default();
-        for (key, value) in meta_sys {
-            let Some(suffix) = rustfs_utils::http::strip_internal_prefix_preserving_case(key) else {
-                continue;
-            };
-            let (canonical_slot, legacy_slot, expected_suffix) = if suffix.eq_ignore_ascii_case(SUFFIX_CRC) {
-                (&mut canonical.checksum, &mut legacy.checksum, SUFFIX_CRC)
-            } else if suffix.eq_ignore_ascii_case(SUFFIX_PART_CHECKSUMS) {
-                (&mut canonical.part_checksums, &mut legacy.part_checksums, SUFFIX_PART_CHECKSUMS)
-            } else if suffix.eq_ignore_ascii_case(SUFFIX_TRANSITION_STATUS) {
-                (&mut canonical.transition_status, &mut legacy.transition_status, SUFFIX_TRANSITION_STATUS)
-            } else if suffix.eq_ignore_ascii_case(SUFFIX_TRANSITIONED_OBJECTNAME) {
-                (
-                    &mut canonical.transitioned_object,
-                    &mut legacy.transitioned_object,
-                    SUFFIX_TRANSITIONED_OBJECTNAME,
-                )
-            } else if suffix.eq_ignore_ascii_case(SUFFIX_TRANSITIONED_VERSION_ID) {
-                (
-                    &mut canonical.transitioned_version,
-                    &mut legacy.transitioned_version,
-                    SUFFIX_TRANSITIONED_VERSION_ID,
-                )
-            } else if suffix.eq_ignore_ascii_case(SUFFIX_TRANSITIONED_VERSION_STATE) {
-                (
-                    &mut canonical.transitioned_version_state,
-                    &mut legacy.transitioned_version_state,
-                    SUFFIX_TRANSITIONED_VERSION_STATE,
-                )
-            } else if suffix.eq_ignore_ascii_case(SUFFIX_TRANSITION_TIER) {
-                (&mut canonical.transition_tier, &mut legacy.transition_tier, SUFFIX_TRANSITION_TIER)
-            } else {
-                continue;
-            };
-            let slot = if suffix == expected_suffix
-                && (key.starts_with(RUSTFS_INTERNAL_PREFIX) || key.starts_with(rustfs_utils::http::MINIO_INTERNAL_PREFIX))
-            {
-                canonical_slot
-            } else {
-                legacy_slot
-            };
-            if slot.is_some_and(|current| current != value.as_slice()) {
-                return Err(Error::FileCorrupt);
-            }
-            *slot = Some(value.as_slice());
-        }
-        Ok(Self {
-            checksum: canonical.checksum.or(legacy.checksum),
-            part_checksums: canonical.part_checksums.or(legacy.part_checksums),
-            transition_status: canonical.transition_status.or(legacy.transition_status),
-            transitioned_object: canonical.transitioned_object.or(legacy.transitioned_object),
-            transitioned_version: canonical.transitioned_version.or(legacy.transitioned_version),
-            transitioned_version_state: canonical.transitioned_version_state.or(legacy.transitioned_version_state),
-            transition_tier: canonical.transition_tier.or(legacy.transition_tier),
-        })
-    }
-}
-
-struct UniquePartChecksums(HashMap<String, String>);
-
-impl<'de> serde::Deserialize<'de> for UniquePartChecksums {
-    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
-    where
-        D: serde::Deserializer<'de>,
-    {
-        struct UniquePartChecksumsVisitor;
-
-        impl<'de> serde::de::Visitor<'de> for UniquePartChecksumsVisitor {
-            type Value = UniquePartChecksums;
-
-            fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-                formatter.write_str("an array of unique checksum name and value pairs")
-            }
-
-            fn visit_seq<A>(self, mut seq: A) -> std::result::Result<Self::Value, A::Error>
-            where
-                A: serde::de::SeqAccess<'de>,
-            {
-                let mut checksums = HashMap::with_capacity(seq.size_hint().unwrap_or_default());
-                while let Some((key, value)) = seq.next_element::<(String, String)>()? {
-                    if checksums.insert(key, value).is_some() {
-                        return Err(serde::de::Error::custom("duplicate part checksum name"));
-                    }
-                }
-                Ok(UniquePartChecksums(checksums))
-            }
-        }
-
-        deserializer.deserialize_seq(UniquePartChecksumsVisitor)
-    }
-}
-
-impl FileInfo {
-    pub fn hydrate_data_movement_part_checksums(&mut self) -> Result<()> {
-        let present = self
-            .metadata
-            .keys()
-            .any(|key| has_internal_suffix(key, SUFFIX_PART_CHECKSUMS));
-        if !present {
-            return Ok(());
-        }
-        let encoded = rustfs_utils::http::get_consistent_str(&self.metadata, SUFFIX_PART_CHECKSUMS).ok_or(Error::FileCorrupt)?;
-        let persisted = serde_json::from_str::<Vec<(usize, UniquePartChecksums)>>(encoded).map_err(|_| Error::FileCorrupt)?;
-        let mut part_indices = HashMap::with_capacity(self.parts.len());
-        for (index, part) in self.parts.iter().enumerate() {
-            if part_indices.insert(part.number, index).is_some() {
-                return Err(Error::FileCorrupt);
-            }
-        }
-        for (part_number, UniquePartChecksums(checksums)) in persisted {
-            let index = part_indices.remove(&part_number).ok_or(Error::FileCorrupt)?;
-            let part = self.parts.get_mut(index).ok_or(Error::FileCorrupt)?;
-            part.checksums = Some(checksums);
-        }
-        Ok(())
+fn transition_version_state_bytes(state: TransitionVersionState) -> &'static [u8] {
+    match state {
+        TransitionVersionState::Unknown => b"unknown",
+        TransitionVersionState::KnownDisabled => b"known-disabled",
+        TransitionVersionState::SuspendedNull => b"suspended-null",
+        TransitionVersionState::Exact => b"exact",
    }
 }

@@ -441,10 +322,21 @@ fn set_transition_version_state(meta_sys: &mut HashMap<String, Vec<u8>>, state:
    if state == TransitionVersionState::Unknown {
        remove_bytes(meta_sys, SUFFIX_TRANSITIONED_VERSION_STATE);
    } else {
-        insert_bytes(meta_sys, SUFFIX_TRANSITIONED_VERSION_STATE, state.as_str().as_bytes().to_vec());
+        insert_bytes(
+            meta_sys,
+            SUFFIX_TRANSITIONED_VERSION_STATE,
+            transition_version_state_bytes(state).to_vec(),
+        );
    }
 }

+fn legacy_transitioned_version_id_from_meta_sys(meta_sys: &HashMap<String, Vec<u8>>) -> Option<Uuid> {
+    transitioned_version_from_meta_sys(meta_sys)
+        .ok()
+        .flatten()
+        .and_then(|value| Uuid::parse_str(&value).ok())
+}
+
 fn transitioned_version_bytes(fi: &FileInfo) -> Option<Vec<u8>> {
    fi.transition_version
        .as_ref()
@@ -556,17 +448,6 @@ impl FileMetaShallowVersion {
    pub fn into_fileinfo(&self, volume: &str, path: &str, all_parts: bool) -> Result<FileInfo> {
        self.parse_version_meta()?.into_fileinfo(volume, path, all_parts)
    }
-
-    pub(super) fn to_fileinfo_with_part_checksums(
-        &self,
-        volume: &str,
-        path: &str,
-        all_parts: bool,
-        include_part_checksums: bool,
-    ) -> Result<FileInfo> {
-        self.parse_version_meta()?
-            .to_fileinfo_with_part_checksums(volume, path, all_parts, include_part_checksums)
-    }
 }

 impl TryFrom<FileMetaVersion> for FileMetaShallowVersion {
@@ -888,16 +769,8 @@ impl FileMetaVersion {
    }

    pub fn into_fileinfo(&self, volume: &str, path: &str, all_parts: bool) -> Result<FileInfo> {
-        self.to_fileinfo_with_part_checksums(volume, path, all_parts, true)
-    }
-
-    pub(super) fn to_fileinfo_with_part_checksums(
-        &self,
-        volume: &str,
-        path: &str,
-        all_parts: bool,
-        include_part_checksums: bool,
-    ) -> Result<FileInfo> {
+        // Only the Object arm carries part arrays and can fail the length guard; the
+        // Legacy and Delete arms have no part arrays and stay infallible.
        let mut fi = match self.version_type {
            VersionType::Invalid | VersionType::Legacy => {
                if let Some(ref legacy) = self.legacy_object {
@@ -915,14 +788,14 @@ impl FileMetaVersion {
                self.object
                    .as_ref()
                    .unwrap_or(&default_object)
-                    .to_fileinfo_with_part_checksums(volume, path, all_parts, include_part_checksums)?
+                    .into_fileinfo(volume, path, all_parts)?
            }
            VersionType::Delete => {
                let default_marker = MetaDeleteMarker::default();
                self.delete_marker
                    .as_ref()
                    .unwrap_or(&default_marker)
-                    .into_fileinfo(volume, path, all_parts)?
+                    .into_fileinfo(volume, path, all_parts)
            }
        };
        fi.uses_legacy_checksum = self.uses_legacy_checksum;
@@ -2517,18 +2390,7 @@ impl MetaObject {
    }

    pub fn into_fileinfo(&self, volume: &str, path: &str, all_parts: bool) -> Result<FileInfo> {
-        self.to_fileinfo_with_part_checksums(volume, path, all_parts, true)
-    }
-
-    fn to_fileinfo_with_part_checksums(
-        &self,
-        volume: &str,
-        path: &str,
-        all_parts: bool,
-        include_part_checksums: bool,
-    ) -> Result<FileInfo> {
        let version_id = self.version_id.filter(|&vid| !vid.is_nil());
-        let derived_metadata = DerivedInternalMetadata::from_meta_sys(&self.meta_sys)?;

        let parts = if all_parts {
            let n = self.part_numbers.len();
@@ -2612,10 +2474,7 @@ impl MetaObject {
            }
        }

-        let checksum = derived_metadata
-            .checksum
-            .filter(|checksum| !checksum.is_empty())
-            .map(Bytes::copy_from_slice);
+        let checksum = get_bytes(&self.meta_sys, SUFFIX_CRC).map(Bytes::from);

        let erasure = ErasureInfo {
            algorithm: self.erasure_algorithm.to_string(),
@@ -2627,29 +2486,20 @@ impl MetaObject {
            ..Default::default()
        };

-        let transition_status = derived_metadata
-            .transition_status
-            .filter(|value| !value.is_empty())
-            .map(|v| String::from_utf8_lossy(v).to_string())
+        let transition_status = get_bytes(&self.meta_sys, SUFFIX_TRANSITION_STATUS)
+            .map(|v| String::from_utf8_lossy(&v).to_string())
            .unwrap_or_default();
-        let transitioned_objname = derived_metadata
-            .transitioned_object
-            .filter(|value| !value.is_empty())
-            .map(|v| String::from_utf8_lossy(v).to_string())
+        let transitioned_objname = get_bytes(&self.meta_sys, SUFFIX_TRANSITIONED_OBJECTNAME)
+            .map(|v| String::from_utf8_lossy(&v).to_string())
            .unwrap_or_default();
-        let transition_version_state = transition_version_state_from_bytes(derived_metadata.transitioned_version_state)?;
-        let transition_version = transitioned_version_from_bytes(derived_metadata.transitioned_version, transition_version_state);
-        if derived_metadata.transitioned_version_state.is_some() {
-            validate_transition_version_state(transition_version_state, transition_version.as_deref())?;
-        }
+        let transition_version = transitioned_version_from_meta_sys(&self.meta_sys)?;
+        let transition_version_state = transition_version_state_from_meta_sys(&self.meta_sys, transition_version.as_deref())?;
        let transition_version_id = transition_version.as_deref().and_then(|value| Uuid::parse_str(value).ok());
-        let transition_tier = derived_metadata
-            .transition_tier
-            .filter(|value| !value.is_empty())
-            .map(|v| String::from_utf8_lossy(v).to_string())
+        let transition_tier = get_bytes(&self.meta_sys, SUFFIX_TRANSITION_TIER)
+            .map(|v| String::from_utf8_lossy(&v).to_string())
            .unwrap_or_default();

-        let mut file_info = FileInfo {
+        Ok(FileInfo {
            version_id,
            erasure,
            data_dir: self.data_dir,
@@ -2669,11 +2519,7 @@ impl MetaObject {
            transition_version_state,
            transition_tier,
            ..Default::default()
-        };
-        if all_parts && include_part_checksums {
-            file_info.hydrate_data_movement_part_checksums()?;
-        }
-        Ok(file_info)
+        })
    }

    pub fn set_transition(&mut self, fi: &FileInfo) {
@@ -2864,31 +2710,39 @@ fn get_internal_replication_state(metadata: &HashMap<String, String>) -> Option<
            continue;
        }

-        if let Some(sub_key) = strip_internal_prefix_preserving_case(k) {
-            if sub_key.eq_ignore_ascii_case(SUFFIX_REPLICA_TIMESTAMP) {
-                has = true;
-                rs.replica_timestamp = Some(parse_replication_timestamp(v).unwrap_or(OffsetDateTime::UNIX_EPOCH));
-            } else if sub_key.eq_ignore_ascii_case(SUFFIX_REPLICA_STATUS) {
-                has = true;
-                rs.replica_status = ReplicationStatusType::from(v.as_str());
-            } else if sub_key.eq_ignore_ascii_case(SUFFIX_REPLICATION_TIMESTAMP) {
-                has = true;
-                rs.replication_timestamp = Some(parse_replication_timestamp(v).unwrap_or(OffsetDateTime::UNIX_EPOCH))
-            } else if sub_key.eq_ignore_ascii_case(SUFFIX_REPLICATION_STATUS) {
-                has = true;
-                rs.replication_status_internal = Some(v.clone());
-                rs.targets = replication_statuses_map(v.as_str());
-            } else if let Some(arn) = rustfs_utils::http::internal_key_strip_suffix_prefix(k, SUFFIX_REPLICATION_RESET_ARN_PREFIX)
-            {
-                has = true;
-                // Store the canonical full-header key so the map matches
-                // the key `target_reset_header()` produces on the
-                // write/lookup side. Storing the bare ARN keyed the map
-                // inconsistently (bare on read, full on write), which
-                // could drop reset state across merge/reflatten cycles
-                // (backlog#799 B16).
-                rs.reset_statuses_map
-                    .insert(crate::replication::target_reset_header(&arn), v.clone());
+        let sub_key_opt = strip_internal_prefix(k);
+        if let Some(ref sub_key) = sub_key_opt {
+            match sub_key.as_str() {
+                "replica-timestamp" => {
+                    has = true;
+                    rs.replica_timestamp = Some(OffsetDateTime::parse(v, &Rfc3339).unwrap_or(OffsetDateTime::UNIX_EPOCH));
+                }
+                "replica-status" => {
+                    has = true;
+                    rs.replica_status = ReplicationStatusType::from(v.as_str());
+                }
+                "replication-timestamp" => {
+                    has = true;
+                    rs.replication_timestamp = Some(OffsetDateTime::parse(v, &Rfc3339).unwrap_or(OffsetDateTime::UNIX_EPOCH))
+                }
+                "replication-status" => {
+                    has = true;
+                    rs.replication_status_internal = Some(v.clone());
+                    rs.targets = replication_statuses_map(v.as_str());
+                }
+                _ => {
+                    if let Some(arn) = sub_key.strip_prefix("replication-reset-") {
+                        has = true;
+                        // Store the canonical full-header key so the map matches
+                        // the key `target_reset_header()` produces on the
+                        // write/lookup side. Storing the bare ARN keyed the map
+                        // inconsistently (bare on read, full on write), which
+                        // could drop reset state across merge/reflatten cycles
+                        // (backlog#799 B16).
+                        rs.reset_statuses_map
+                            .insert(crate::replication::target_reset_header(arn), v.clone());
+                    }
+                }
            }
        }
    }
@@ -2932,7 +2786,7 @@ impl MetaDeleteMarker {
        contains_key_bytes(&self.meta_sys, SUFFIX_FREE_VERSION)
    }

-    pub fn into_fileinfo(&self, volume: &str, path: &str, _all_parts: bool) -> Result<FileInfo> {
+    pub fn into_fileinfo(&self, volume: &str, path: &str, _all_parts: bool) -> FileInfo {
        let metadata = self
            .meta_sys
            .clone()
@@ -2954,27 +2808,22 @@ impl MetaDeleteMarker {

        if self.free_version() {
            fi.set_tier_free_version();
-            let derived_metadata = DerivedInternalMetadata::from_meta_sys(&self.meta_sys)?;
-            fi.transition_tier = derived_metadata
-                .transition_tier
-                .filter(|value| !value.is_empty())
-                .map(|value| String::from_utf8_lossy(value).to_string())
+            fi.transition_tier = get_bytes(&self.meta_sys, SUFFIX_TRANSITION_TIER)
+                .map(|v| String::from_utf8_lossy(&v).to_string())
                .unwrap_or_default();
-            fi.transitioned_objname = derived_metadata
-                .transitioned_object
-                .filter(|value| !value.is_empty())
-                .map(|value| String::from_utf8_lossy(value).to_string())
+
+            fi.transitioned_objname = get_bytes(&self.meta_sys, SUFFIX_TRANSITIONED_OBJECTNAME)
+                .map(|v| String::from_utf8_lossy(&v).to_string())
                .unwrap_or_default();
-            fi.transition_version_state = transition_version_state_from_bytes(derived_metadata.transitioned_version_state)?;
-            fi.transition_version =
-                transitioned_version_from_bytes(derived_metadata.transitioned_version, fi.transition_version_state);
-            fi.transition_version_id = fi.transition_version.as_deref().and_then(|value| Uuid::parse_str(value).ok());
-            if derived_metadata.transitioned_version_state.is_some() {
-                validate_transition_version_state(fi.transition_version_state, fi.transition_version.as_deref())?;
-            }
+
+            fi.transition_version = transitioned_version_from_meta_sys(&self.meta_sys).ok().flatten();
+            fi.transition_version_id = legacy_transitioned_version_id_from_meta_sys(&self.meta_sys);
+            fi.transition_version_state =
+                transition_version_state_from_meta_sys(&self.meta_sys, fi.transition_version.as_deref())
+                    .unwrap_or(TransitionVersionState::Unknown);
        }

-        Ok(fi)
+        fi
    }

    pub fn encode_to<W: std::io::Write>(&self, wr: &mut W) -> Result<()> {
@@ -3092,13 +2941,6 @@ impl From<FileInfo> for MetaDeleteMarker {
            if !is_internal_key(key) || is_skip_meta_key(key) {
                continue;
            }
-            if rustfs_utils::http::internal_key_strip_suffix_prefix(key, SUFFIX_REPLICATION_RESET_ARN_PREFIX).is_some()
-                || rustfs_utils::http::internal_key_strip_suffix_prefix(key, SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX)
-                    .is_some()
-            {
-                meta_sys.insert(key.clone(), metadata_value.as_bytes().to_vec());
-                continue;
-            }
            let Some(suffix) = strip_internal_prefix(key) else {
                continue;
            };
@@ -3140,11 +2982,6 @@ impl From<FileInfo> for MetaDeleteMarker {
        if !value.transition_tier.is_empty() {
            insert_bytes(&mut meta_sys, SUFFIX_TRANSITION_TIER, value.transition_tier.as_bytes().to_vec());
        }
-        if let Some(state) = value.replication_state_internal.as_ref() {
-            persist_delete_marker_replication_state(&mut meta_sys, state);
-            persist_reset_statuses(&mut meta_sys, &state.reset_statuses_map);
-            persist_target_delete_marker_versions(&mut meta_sys, &state.target_delete_marker_version_ids, &value.metadata);
-        }
        Self {
            version_id: value.version_id,
            mod_time: value.mod_time,
@@ -3441,7 +3278,6 @@ pub fn file_info_from_raw(
        FileInfoOpts {
            data: read_data,
            include_free_versions,
-            include_part_checksums: true,
        },
    )
 }
@@ -3449,7 +3285,6 @@ pub fn file_info_from_raw(
 pub struct FileInfoOpts {
    pub data: bool,
    pub include_free_versions: bool,
-    pub include_part_checksums: bool,
 }

 pub fn get_file_info(buf: &[u8], volume: &str, path: &str, version_id: &str, opts: FileInfoOpts) -> Result<FileInfo> {
@@ -3474,11 +3309,7 @@ pub fn get_file_info(buf: &[u8], volume: &str, path: &str, version_id: &str, opt
        });
    }

-    let fi = if opts.include_part_checksums {
-        meta.into_fileinfo(volume, path, version_id, opts.data, opts.include_free_versions, true)?
-    } else {
-        meta.into_fileinfo_without_part_checksums(volume, path, version_id, opts.data, opts.include_free_versions)?
-    };
+    let fi = meta.into_fileinfo(volume, path, version_id, opts.data, opts.include_free_versions, true)?;
    Ok(fi)
 }

@@ -3724,56 +3555,6 @@ mod tests {
        assert!(!converted.meta_sys.contains_key("content-type"));
    }

-    #[test]
-    fn delete_marker_conversion_does_not_lowercase_dynamic_replication_targets() {
-        let arn = "arn:rustfs:replication:us-east-1:TenantA:bucket";
-        let reset_suffix = format!("{SUFFIX_REPLICATION_RESET_ARN_PREFIX}{arn}");
-        let version_suffix = format!("{SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX}{arn}");
-        let mut marker = FileInfo::default();
-        marker.metadata.insert(
-            format!("{}{reset_suffix}", rustfs_utils::http::MINIO_INTERNAL_PREFIX),
-            "2026-08-12T00:00:00Z;COMPLETED".to_string(),
-        );
-        marker.metadata.insert(
-            format!("{}{version_suffix}", rustfs_utils::http::MINIO_INTERNAL_PREFIX),
-            "remote-version".to_string(),
-        );
-        marker.replication_state_internal = get_internal_replication_state(&marker.metadata);
-
-        let converted = MetaDeleteMarker::from(marker);
-
-        assert!(converted.meta_sys.keys().any(|key| key.ends_with(&reset_suffix)));
-        assert!(converted.meta_sys.keys().any(|key| key.ends_with(&version_suffix)));
-        assert!(!converted.meta_sys.keys().any(|key| key.contains("tenanta")));
-
-        let mut conflicting = FileInfo::default();
-        conflicting
-            .metadata
-            .insert(format!("{RUSTFS_INTERNAL_PREFIX}{version_suffix}"), "remote-version-a".to_string());
-        conflicting.metadata.insert(
-            format!("{}{version_suffix}", rustfs_utils::http::MINIO_INTERNAL_PREFIX),
-            "remote-version-b".to_string(),
-        );
-        conflicting.replication_state_internal = get_internal_replication_state(&conflicting.metadata);
-        assert!(
-            conflicting
-                .replication_state_internal
-                .as_ref()
-                .is_some_and(|state| state.target_delete_marker_version_ids_corrupt)
-        );
-
-        let roundtrip = MetaDeleteMarker::from(conflicting)
-            .into_fileinfo("bucket", "object", false)
-            .expect("dynamic replication aliases should remain decodable");
-        assert!(
-            roundtrip
-                .replication_state_internal
-                .as_ref()
-                .is_some_and(|state| state.target_delete_marker_version_ids_corrupt),
-            "conflicting dynamic aliases must remain corrupt across persistence"
-        );
-    }
-
    #[derive(Serialize)]
    enum LegacyDeleteVersionTypeFixture {
        #[serde(rename = "DeleteMarker")]
@@ -3882,138 +3663,6 @@ mod tests {
        assert!(matches!(res, Err(Error::FileCorrupt)), "short part_sizes must map to FileCorrupt");
    }

-    #[test]
-    fn into_fileinfo_rejects_conflicting_derived_internal_aliases() {
-        for suffix in [
-            SUFFIX_CRC,
-            SUFFIX_TRANSITION_STATUS,
-            SUFFIX_TRANSITIONED_OBJECTNAME,
-            SUFFIX_TRANSITIONED_VERSION_ID,
-            SUFFIX_TRANSITIONED_VERSION_STATE,
-            SUFFIX_TRANSITION_TIER,
-        ] {
-            let mut meta_sys = HashMap::from([(format!("{RUSTFS_INTERNAL_PREFIX}{suffix}"), vec![0xff, 1])]);
-            meta_sys.insert(format!("{}{suffix}", rustfs_utils::http::MINIO_INTERNAL_PREFIX), vec![0xfe, 2]);
-            let object = MetaObject {
-                meta_sys,
-                ..Default::default()
-            };
-
-            assert_eq!(
-                object
-                    .into_fileinfo("bucket", "key", false)
-                    .expect_err("conflicting aliases must fail closed"),
-                Error::FileCorrupt,
-                "suffix {suffix}"
-            );
-        }
-    }
-
-    #[test]
-    fn into_fileinfo_recovers_noncanonical_binary_checksum_alias() {
-        let checksum = vec![0xff, 0x00, 0x80, 0x01];
-        let object = MetaObject {
-            meta_sys: HashMap::from([("X-Minio-Internal-crc".to_string(), checksum.clone())]),
-            ..Default::default()
-        };
-
-        let file_info = object
-            .into_fileinfo("bucket", "key", false)
-            .expect("a single legacy checksum alias should remain readable");
-
-        assert_eq!(file_info.checksum.as_deref(), Some(checksum.as_slice()));
-    }
-
-    #[test]
-    fn into_fileinfo_prefers_canonical_rewrite_over_stale_mixed_case_alias() {
-        let checksum = vec![0xff, 0x00, 0x80, 0x01];
-        let mut object = MetaObject {
-            meta_sys: HashMap::from([("X-Minio-Internal-crc".to_string(), b"stale".to_vec())]),
-            ..Default::default()
-        };
-        insert_bytes(&mut object.meta_sys, SUFFIX_CRC, checksum.clone());
-
-        let file_info = object
-            .into_fileinfo("bucket", "key", false)
-            .expect("canonical rewrites should supersede legacy mixed-case aliases");
-
-        assert_eq!(file_info.checksum.as_deref(), Some(checksum.as_slice()));
-    }
-
-    #[test]
-    fn into_fileinfo_recovers_data_movement_part_checksums() {
-        let mut object = object_with_parts(vec![1], vec![16], vec![16]);
-        insert_bytes(&mut object.meta_sys, SUFFIX_PART_CHECKSUMS, br#"[[1,[["CRC32C","AAAAAA=="]]]]"#.to_vec());
-
-        let file_info = object
-            .into_fileinfo("bucket", "key", true)
-            .expect("data movement part checksums should decode");
-
-        assert_eq!(
-            file_info.parts[0]
-                .checksums
-                .as_ref()
-                .and_then(|checksums| checksums.get("CRC32C"))
-                .map(String::as_str),
-            Some("AAAAAA==")
-        );
-
-        let mut deferred = object
-            .to_fileinfo_with_part_checksums("bucket", "key", true, false)
-            .expect("quorum candidates should retain raw checksum metadata");
-        assert!(deferred.parts[0].checksums.is_none());
-        deferred
-            .hydrate_data_movement_part_checksums()
-            .expect("the selected candidate should hydrate checksums once");
-        assert_eq!(deferred.parts[0].checksums, file_info.parts[0].checksums);
-
-        insert_bytes(&mut object.meta_sys, SUFFIX_PART_CHECKSUMS, b"not-json".to_vec());
-        assert_eq!(
-            object
-                .into_fileinfo("bucket", "key", true)
-                .expect_err("malformed data movement part checksums must fail closed"),
-            Error::FileCorrupt
-        );
-
-        for encoded in [
-            br#"[[1,[["CRC32C","AAAAAA=="]]],[1,[["CRC32C","BBBBBB=="]]]]"#.as_slice(),
-            br#"[[1,[["CRC32C","AAAAAA=="],["CRC32C","BBBBBB=="]]]]"#.as_slice(),
-        ] {
-            insert_bytes(&mut object.meta_sys, SUFFIX_PART_CHECKSUMS, encoded.to_vec());
-            assert_eq!(
-                object
-                    .into_fileinfo("bucket", "key", true)
-                    .expect_err("duplicate part checksum keys must fail closed"),
-                Error::FileCorrupt
-            );
-        }
-
-        insert_bytes(&mut object.meta_sys, SUFFIX_PART_CHECKSUMS, br#"[[2,[["CRC32C","AAAAAA=="]]]]"#.to_vec());
-        assert_eq!(
-            object
-                .into_fileinfo("bucket", "key", true)
-                .expect_err("a sidecar for an unknown part must fail closed"),
-            Error::FileCorrupt
-        );
-
-        object.meta_sys = HashMap::from([
-            (
-                format!("{RUSTFS_INTERNAL_PREFIX}{SUFFIX_PART_CHECKSUMS}"),
-                br#"[[1,[["CRC32C","AAAAAA=="]]]]"#.to_vec(),
-            ),
-            (
-                format!("{}{}", rustfs_utils::http::MINIO_INTERNAL_PREFIX, SUFFIX_PART_CHECKSUMS),
-                br#"[[1,[["CRC32C","BBBBBB=="]]]]"#.to_vec(),
-            ),
-        ]);
-        assert_eq!(
-            object
-                .into_fileinfo("bucket", "key", true)
-                .expect_err("conflicting sidecar aliases must fail closed"),
-            Error::FileCorrupt
-        );
-    }
-
    #[test]
    fn into_fileinfo_rejects_short_part_actual_sizes_including_empty() {
        let obj = object_with_parts(vec![1, 2], vec![10, 20], vec![]);
@@ -4581,31 +4230,6 @@ mod tests {
        assert_eq!(fi.transition_version_state, TransitionVersionState::Unknown);
    }

-    #[test]
-    fn meta_object_transition_exact_rejects_legacy_raw_uuid_encoding() {
-        let mut sys = HashMap::new();
-        insert_bytes(&mut sys, SUFFIX_TRANSITIONED_VERSION_ID, sample_version_id().as_bytes().to_vec());
-        insert_bytes(&mut sys, SUFFIX_TRANSITIONED_VERSION_STATE, b"exact".to_vec());
-
-        let err = make_meta_object_with_sys(sys)
-            .into_fileinfo("b", "k", false)
-            .expect_err("exact remote versions must use their UTF-8 provider representation");
-
-        assert_eq!(err, Error::FileCorrupt);
-    }
-
-    #[test]
-    fn meta_object_transition_version_id_mixed_case_alias_is_recovered() {
-        let id = sample_version_id();
-        let sys = HashMap::from([("X-Minio-Internal-transitioned-versionID".to_string(), id.as_bytes().to_vec())]);
-        let fi = make_meta_object_with_sys(sys)
-            .into_fileinfo("b", "k", false)
-            .expect("a legacy mixed-case transition version alias should decode");
-
-        assert_eq!(fi.transition_version_id, Some(id));
-        assert_eq!(fi.transition_version, Some(id.to_string()));
-    }
-
    #[test]
    fn meta_object_transition_version_id_opaque_text_is_preserved() {
        let mut sys = HashMap::new();
@@ -4647,10 +4271,8 @@ mod tests {
                .map(Vec::as_slice),
            Some(b"exact".as_slice())
        );
-        let persisted_version = get_consistent_bytes(&object.meta_sys, SUFFIX_TRANSITIONED_VERSION_ID);
        assert_eq!(
-            transitioned_version_from_bytes(persisted_version, TransitionVersionState::Unknown)
-                .and_then(|value| Uuid::parse_str(&value).ok()),
+            legacy_transitioned_version_id_from_meta_sys(&object.meta_sys),
            Some(id),
            "UUID exact writes must remain readable by the legacy UUID consumer"
        );
@@ -4659,26 +4281,6 @@ mod tests {
        assert_eq!(decoded.transition_version.as_deref(), Some(expected_version.as_str()));
    }

-    #[test]
-    fn meta_object_transition_version_state_exact_preserves_sixteen_byte_opaque_text() {
-        let expected_version = "opaque.wasabi_01";
-        assert_eq!(expected_version.len(), 16);
-        let fi = FileInfo {
-            transition_status: "complete".to_string(),
-            transition_version: Some(expected_version.to_string()),
-            transition_version_state: TransitionVersionState::Exact,
-            ..Default::default()
-        };
-
-        let decoded = MetaObject::from(fi)
-            .into_fileinfo("b", "k", false)
-            .expect("exact opaque transition version should round trip");
-
-        assert_eq!(decoded.transition_version.as_deref(), Some(expected_version));
-        assert_eq!(decoded.transition_version_id, None);
-        assert_eq!(decoded.transition_version_state, TransitionVersionState::Exact);
-    }
-
    #[test]
    fn set_transition_known_disabled_removes_stale_version_dual_keys() {
        let mut meta_sys = HashMap::new();
@@ -4773,8 +4375,7 @@ mod tests {
            mod_time: None,
            meta_sys: sys,
        }
-        .into_fileinfo("b", "k", false)
-        .expect("nil tier version should remain an absent remote version");
+        .into_fileinfo("b", "k", false);
        assert_eq!(fi.transition_version_id, None);
    }

@@ -4789,8 +4390,7 @@ mod tests {
            mod_time: None,
            meta_sys: sys,
        }
-        .into_fileinfo("b", "k", false)
-        .expect("legacy binary UUID tier version should decode");
+        .into_fileinfo("b", "k", false);
        assert_eq!(fi.transition_version_id, Some(id));
        assert_eq!(fi.transition_version, Some(id.to_string()));
    }
@@ -4807,8 +4407,7 @@ mod tests {
            mod_time: Some(sample_mod_time()),
            meta_sys: sys,
        }
-        .into_fileinfo("b", "k", false)
-        .expect("opaque tier version should remain readable");
+        .into_fileinfo("b", "k", false);

        assert_eq!(fi.transition_version_id, None);
        assert_eq!(fi.transition_version.as_deref(), Some("opaque-generation-42"));
@@ -4830,67 +4429,12 @@ mod tests {
            mod_time: Some(sample_mod_time()),
            meta_sys: sys,
        }
-        .into_fileinfo("b", "k", false)
-        .expect("mixed-case tier aliases should decode");
+        .into_fileinfo("b", "k", false);

        assert_eq!(fi.transition_version_id, Some(id));
        assert_eq!(fi.transition_version, Some(id.to_string()));
    }

-    #[test]
-    fn delete_marker_free_version_recovers_mixed_case_transition_aliases() {
-        let id = sample_version_id();
-        let id_text = id.to_string();
-        let mut sys = HashMap::new();
-        insert_bytes(&mut sys, SUFFIX_FREE_VERSION, vec![]);
-        for (suffix, value) in [
-            (SUFFIX_TRANSITIONED_VERSION_ID, id_text.as_bytes()),
-            (SUFFIX_TRANSITIONED_VERSION_STATE, b"exact".as_slice()),
-            (SUFFIX_TRANSITION_TIER, b"WARM".as_slice()),
-            (SUFFIX_TRANSITIONED_OBJECTNAME, b"remote-object".as_slice()),
-        ] {
-            sys.insert(format!("X-Minio-Internal-{suffix}"), value.to_vec());
-        }
-
-        let fi = MetaDeleteMarker {
-            version_id: Some(sample_version_id()),
-            mod_time: Some(sample_mod_time()),
-            meta_sys: sys,
-        }
-        .into_fileinfo("b", "k", false)
-        .expect("mixed-case tier aliases should decode");
-
-        assert_eq!(fi.transition_version_id, Some(id));
-        assert_eq!(fi.transition_version, Some(id.to_string()));
-        assert_eq!(fi.transition_version_state, TransitionVersionState::Exact);
-        assert_eq!(fi.transition_tier, "WARM");
-        assert_eq!(fi.transitioned_objname, "remote-object");
-    }
-
-    #[test]
-    fn delete_marker_free_version_rejects_conflicting_transition_aliases() {
-        let mut sys = HashMap::new();
-        insert_bytes(&mut sys, SUFFIX_FREE_VERSION, vec![]);
-        sys.insert(
-            format!("{RUSTFS_INTERNAL_PREFIX}{SUFFIX_TRANSITIONED_VERSION_ID}"),
-            b"source-version".to_vec(),
-        );
-        sys.insert(
-            format!("{}{}", rustfs_utils::http::MINIO_INTERNAL_PREFIX, SUFFIX_TRANSITIONED_VERSION_ID),
-            b"target-version".to_vec(),
-        );
-
-        let err = MetaDeleteMarker {
-            version_id: Some(sample_version_id()),
-            mod_time: Some(sample_mod_time()),
-            meta_sys: sys,
-        }
-        .into_fileinfo("b", "k", false)
-        .expect_err("conflicting transition aliases must fail closed");
-
-        assert_eq!(err, Error::FileCorrupt);
-    }
-
    #[test]
    fn version_header_sorts_before_prefers_object_over_delete_marker_on_equal_mod_time() {
        let object = FileMetaVersionHeader {
@@ -5214,7 +4758,7 @@ mod tests {

    #[test]
    fn target_delete_marker_version_metadata_is_forward_and_backward_compatible() {
-        let arn = "arn:rustfs:replication:us-east-1:TenantA:bucket";
+        let arn = "arn:rustfs:replication:us-east-1:target:bucket";
        let suffix = format!("{}{arn}", rustfs_utils::http::SUFFIX_REPLICATION_DELETE_MARKER_VERSION_ARN_PREFIX);
        let mut metadata = HashMap::from([(format!("{RUSTFS_INTERNAL_PREFIX}replication-status"), format!("{arn}=COMPLETED;"))]);

@@ -5259,7 +4803,7 @@ mod tests {
        // must keep it keyed by `target_reset_header(arn)` (not the bare ARN) so
        // `ReplicationState::target_state` finds it after a round trip
        // (backlog#799 B16).
-        let arn = "arn:rustfs:replication:us-east-1:TenantA:bucket";
+        let arn = "arn:rustfs:replication:us-east-1:target:bucket";
        let ts = "2026-06-30T00:00:00Z;reset-1".to_string();
        let key = crate::replication::target_reset_header(arn);
        let mut metadata = HashMap::new();
@@ -5278,33 +4822,6 @@ mod tests {
        );
    }

-    #[test]
-    fn get_internal_replication_state_accepts_rfc3339_and_rustfs_display_timestamps() {
-        let replica_timestamp = OffsetDateTime::UNIX_EPOCH + time::Duration::SECOND;
-        let replication_timestamp = replica_timestamp + time::Duration::SECOND;
-        let metadata = HashMap::from([
-            (format!("{RUSTFS_INTERNAL_PREFIX}{SUFFIX_REPLICA_STATUS}"), "REPLICA".to_string()),
-            (
-                format!("{RUSTFS_INTERNAL_PREFIX}{SUFFIX_REPLICA_TIMESTAMP}"),
-                replica_timestamp.to_string(),
-            ),
-            (
-                format!("{RUSTFS_INTERNAL_PREFIX}{SUFFIX_REPLICATION_STATUS}"),
-                "arn:rustfs:replication:us-east-1:TenantA:bucket=COMPLETED;".to_string(),
-            ),
-            (
-                format!("{RUSTFS_INTERNAL_PREFIX}{SUFFIX_REPLICATION_TIMESTAMP}"),
-                replication_timestamp
-                    .format(&Rfc3339)
-                    .expect("RFC3339 timestamp should format"),
-            ),
-        ]);
-
-        let state = get_internal_replication_state(&metadata).expect("replication metadata should parse");
-        assert_eq!(state.replica_timestamp, Some(replica_timestamp));
-        assert_eq!(state.replication_timestamp, Some(replication_timestamp));
-    }
-
    // ---- Header signature (backlog#861 / B12) ----

    fn signed_object() -> MetaObject {
@@ -157,7 +157,7 @@ impl MetaCacheEntry {
                });
            }

-            let fi = fm.into_fileinfo_without_part_checksums(bucket, self.name.as_str(), "", false, false)?;
+            let fi = fm.into_fileinfo(bucket, self.name.as_str(), "", false, false, true)?;
            return Ok(fi);
        }

@@ -169,7 +169,6 @@ impl MetaCacheEntry {
            FileInfoOpts {
                data: false,
                include_free_versions: false,
-                include_part_checksums: false,
            },
        )
    }
@@ -2158,38 +2157,4 @@ mod tests {
        let inner = caught.expect("file_info_versions must not panic");
        assert!(matches!(inner, Err(Error::FileCorrupt)), "expected FileCorrupt");
    }
-
-    #[test]
-    fn metacache_to_fileinfo_ignores_part_checksum_sidecar_regardless_of_cache_state() {
-        let mut meta = FileMeta::load(&create_real_xlmeta().expect("create real xl.meta")).expect("load real xl.meta");
-        let version_id = Uuid::parse_str("01234567-89ab-cdef-0123-456789abcdef").expect("valid fixture version id");
-        let (index, mut version) = meta.find_version(Some(version_id)).expect("find fixture object version");
-        rustfs_utils::http::insert_bytes(
-            &mut version.object.as_mut().expect("fixture object").meta_sys,
-            rustfs_utils::http::SUFFIX_PART_CHECKSUMS,
-            b"not-json".to_vec(),
-        );
-        meta.versions[index] = FileMetaShallowVersion::try_from(version).expect("replace fixture object version");
-        let encoded = meta.marshal_msg().expect("marshal object metadata");
-
-        let uncached = MetaCacheEntry {
-            name: "object".to_string(),
-            metadata: encoded.clone(),
-            cached: None,
-            reusable: false,
-        }
-        .to_fileinfo("bucket")
-        .expect("uncached metacache conversion must stay lazy");
-        let cached = MetaCacheEntry {
-            name: "object".to_string(),
-            metadata: encoded,
-            cached: Some(meta),
-            reusable: false,
-        }
-        .to_fileinfo("bucket")
-        .expect("cached metacache conversion must stay lazy");
-
-        assert_eq!(cached, uncached);
-        assert!(cached.parts.iter().all(|part| part.checksums.is_none()));
-    }
 }
@@ -14,8 +14,6 @@

 //! test endpoint index settings

-#![recursion_limit = "256"]
-
 use std::net::SocketAddr;
 use tempfile::TempDir;
 use tokio_util::sync::CancellationToken;
@@ -22,8 +22,6 @@
 //! bucket-metadata-sys OnceCell) — under `cargo nextest` each test runs
 //! in its own process so the OnceCell never collides.

-#![recursion_limit = "256"]
-
 use http::HeaderMap;
 use rustfs_common::heal_channel::{HealOpts, HealScanMode};
 use rustfs_heal::heal::{
@@ -21,8 +21,6 @@
 //! These drive the REAL `ECStoreHealStorage` + `ECStore` against real disks.
 //! Every test is `#[serial]`; under `cargo nextest` each runs in its own process.

-#![recursion_limit = "256"]
-
 use http::HeaderMap;
 use rustfs_common::heal_channel::{HealOpts, HealScanMode};
 use rustfs_heal::heal::storage::{
@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

-#![recursion_limit = "256"]
-
 use http::HeaderMap;
 use rustfs_common::heal_channel::{HealOpts, HealScanMode};
 use rustfs_heal::heal::{
@@ -14,23 +14,19 @@

 use crate::IamStorageError;
 use rustfs_policy::policy::Error as PolicyError;
-use std::sync::Arc;

 pub type Result<T> = core::result::Result<T, Error>;

 #[derive(thiserror::Error, Debug)]
 pub enum Error {
-    // Arc payloads keep Clone variant-preserving for the non-cloneable inner
-    // errors (backlog#1831 PR2). Display is unchanged; the source() chain is
-    // not forwarded (Arc<E> does not implement std::error::Error).
-    #[error("{0}")]
-    PolicyError(Arc<PolicyError>),
+    #[error(transparent)]
+    PolicyError(#[from] PolicyError),

    #[error("{0}")]
    StringError(String),

    #[error("crypto: {0}")]
-    CryptoError(Arc<rustfs_crypto::Error>),
+    CryptoError(#[from] rustfs_crypto::Error),

    #[error("user '{0}' does not exist")]
    NoSuchUser(String),
@@ -62,6 +58,15 @@ pub enum Error {
    #[error("not initialized")]
    IamSysNotInitialized,

+    #[error("invalid service type: {0}")]
+    InvalidServiceType(String),
+
+    #[error("malformed credential")]
+    ErrCredMalformed,
+
+    #[error("CredNotInitialized")]
+    CredNotInitialized,
+
    #[error("invalid access key length")]
    InvalidAccessKeyLength,

@@ -74,12 +79,27 @@ pub enum Error {
    #[error("group name contains reserved characters =,")]
    GroupNameContainsReservedChars,

+    #[error("jwt err {0}")]
+    JWTError(jsonwebtoken::errors::Error),
+
+    #[error("no access key")]
+    NoAccessKey,
+
+    #[error("invalid token")]
+    InvalidToken,
+
+    #[error("invalid access_key")]
+    InvalidAccessKey,
+
    #[error("access key is already in use")]
    AccessKeyAlreadyExists,

    #[error("action not allowed")]
    IAMActionNotAllowed,

+    #[error("invalid expiration")]
+    InvalidExpiration,
+
    #[error("no secret key with access key")]
    NoSecretKeyWithAccessKey,

@@ -108,8 +128,9 @@ impl PartialEq for Error {
            (Error::NoSuchServiceAccount(a), Error::NoSuchServiceAccount(b)) => a == b,
            (Error::NoSuchTempAccount(a), Error::NoSuchTempAccount(b)) => a == b,
            (Error::NoSuchGroup(a), Error::NoSuchGroup(b)) => a == b,
+            (Error::InvalidServiceType(a), Error::InvalidServiceType(b)) => a == b,
            (Error::Io(a), Error::Io(b)) => a.kind() == b.kind() && a.to_string() == b.to_string(),
-            // For complex types like PolicyError and CryptoError, compare string representations
+            // For complex types like PolicyError, CryptoError, JWTError, compare string representations
            (a, b) => std::mem::discriminant(a) == std::mem::discriminant(b) && a.to_string() == b.to_string(),
        }
    }
@@ -118,9 +139,9 @@ impl PartialEq for Error {
 impl Clone for Error {
    fn clone(&self) -> Self {
        match self {
-            Error::PolicyError(e) => Error::PolicyError(Arc::clone(e)),
+            Error::PolicyError(e) => Error::StringError(e.to_string()), // Convert to string since PolicyError may not be cloneable
            Error::StringError(s) => Error::StringError(s.clone()),
-            Error::CryptoError(e) => Error::CryptoError(Arc::clone(e)),
+            Error::CryptoError(e) => Error::StringError(format!("crypto: {e}")), // Convert to string
            Error::NoSuchUser(s) => Error::NoSuchUser(s.clone()),
            Error::NoSuchAccount(s) => Error::NoSuchAccount(s.clone()),
            Error::NoSuchServiceAccount(s) => Error::NoSuchServiceAccount(s.clone()),
@@ -131,12 +152,20 @@ impl Clone for Error {
            Error::GroupNotEmpty => Error::GroupNotEmpty,
            Error::InvalidArgument => Error::InvalidArgument,
            Error::IamSysNotInitialized => Error::IamSysNotInitialized,
+            Error::InvalidServiceType(s) => Error::InvalidServiceType(s.clone()),
+            Error::ErrCredMalformed => Error::ErrCredMalformed,
+            Error::CredNotInitialized => Error::CredNotInitialized,
            Error::InvalidAccessKeyLength => Error::InvalidAccessKeyLength,
            Error::InvalidSecretKeyLength => Error::InvalidSecretKeyLength,
            Error::ContainsReservedChars => Error::ContainsReservedChars,
            Error::GroupNameContainsReservedChars => Error::GroupNameContainsReservedChars,
+            Error::JWTError(e) => Error::StringError(format!("jwt err {e}")), // Convert to string
+            Error::NoAccessKey => Error::NoAccessKey,
+            Error::InvalidToken => Error::InvalidToken,
+            Error::InvalidAccessKey => Error::InvalidAccessKey,
            Error::AccessKeyAlreadyExists => Error::AccessKeyAlreadyExists,
            Error::IAMActionNotAllowed => Error::IAMActionNotAllowed,
+            Error::InvalidExpiration => Error::InvalidExpiration,
            Error::NoSecretKeyWithAccessKey => Error::NoSecretKeyWithAccessKey,
            Error::NoAccessKeyWithSecretKey => Error::NoAccessKeyWithSecretKey,
            Error::PolicyTooLarge => Error::PolicyTooLarge,
@@ -147,18 +176,6 @@ impl Clone for Error {
    }
 }

-impl From<PolicyError> for Error {
-    fn from(e: PolicyError) -> Self {
-        Error::PolicyError(Arc::new(e))
-    }
-}
-
-impl From<rustfs_crypto::Error> for Error {
-    fn from(e: rustfs_crypto::Error) -> Self {
-        Error::CryptoError(Arc::new(e))
-    }
-}
-
 impl Error {
    pub fn other<E>(error: E) -> Self
    where
@@ -191,10 +208,16 @@ impl From<rustfs_policy::error::Error> for Error {
        match e {
            rustfs_policy::error::Error::PolicyTooLarge => Error::PolicyTooLarge,
            rustfs_policy::error::Error::InvalidArgument => Error::InvalidArgument,
+            rustfs_policy::error::Error::InvalidServiceType(s) => Error::InvalidServiceType(s),
            rustfs_policy::error::Error::IAMActionNotAllowed => Error::IAMActionNotAllowed,
+            rustfs_policy::error::Error::InvalidExpiration => Error::InvalidExpiration,
+            rustfs_policy::error::Error::NoAccessKey => Error::NoAccessKey,
+            rustfs_policy::error::Error::InvalidToken => Error::InvalidToken,
+            rustfs_policy::error::Error::InvalidAccessKey => Error::InvalidAccessKey,
            rustfs_policy::error::Error::NoSecretKeyWithAccessKey => Error::NoSecretKeyWithAccessKey,
            rustfs_policy::error::Error::NoAccessKeyWithSecretKey => Error::NoAccessKeyWithSecretKey,
            rustfs_policy::error::Error::Io(e) => Error::Io(e),
+            rustfs_policy::error::Error::JWTError(e) => Error::JWTError(e),
            rustfs_policy::error::Error::NoSuchUser(s) => Error::NoSuchUser(s),
            rustfs_policy::error::Error::NoSuchAccount(s) => Error::NoSuchAccount(s),
            rustfs_policy::error::Error::NoSuchServiceAccount(s) => Error::NoSuchServiceAccount(s),
@@ -207,22 +230,13 @@ impl From<rustfs_policy::error::Error> for Error {
            rustfs_policy::error::Error::InvalidSecretKeyLength => Error::InvalidSecretKeyLength,
            rustfs_policy::error::Error::ContainsReservedChars => Error::ContainsReservedChars,
            rustfs_policy::error::Error::GroupNameContainsReservedChars => Error::GroupNameContainsReservedChars,
+            rustfs_policy::error::Error::CredNotInitialized => Error::CredNotInitialized,
            rustfs_policy::error::Error::IamSysNotInitialized => Error::IamSysNotInitialized,
-            rustfs_policy::error::Error::PolicyError(e) => Error::PolicyError(Arc::new(e)),
+            rustfs_policy::error::Error::PolicyError(e) => Error::PolicyError(e),
            rustfs_policy::error::Error::StringError(s) => Error::StringError(s),
-            rustfs_policy::error::Error::CryptoError(e) => Error::CryptoError(Arc::new(e)),
+            rustfs_policy::error::Error::CryptoError(e) => Error::CryptoError(e),
+            rustfs_policy::error::Error::ErrCredMalformed => Error::ErrCredMalformed,
            rustfs_policy::error::Error::IamSysAlreadyInitialized => Error::IamSysAlreadyInitialized,
-            // These policy variants had dead same-name twins on iam::Error (zero
-            // construction and zero match sites, removed in backlog#1831); the
-            // message is preserved through StringError instead.
-            err @ (rustfs_policy::error::Error::InvalidServiceType(_)
-            | rustfs_policy::error::Error::InvalidExpiration
-            | rustfs_policy::error::Error::NoAccessKey
-            | rustfs_policy::error::Error::InvalidToken
-            | rustfs_policy::error::Error::InvalidAccessKey
-            | rustfs_policy::error::Error::JWTError(_)
-            | rustfs_policy::error::Error::CredNotInitialized
-            | rustfs_policy::error::Error::ErrCredMalformed) => Error::StringError(err.to_string()),
        }
    }
 }
@@ -401,31 +415,6 @@ mod tests {
        assert!(converted_io.to_string().contains("access denied"));
    }

-    #[test]
-    fn clone_preserves_variant_identity_and_message() {
-        // backlog#1831 PR2: cloning must never demote a variant to a different
-        // one (the old Clone stringified PolicyError/CryptoError into
-        // StringError). Pin discriminant and rendered message across clone.
-        let errors = vec![
-            Error::PolicyError(Arc::new(PolicyError::NonAction)),
-            Error::CryptoError(Arc::new(rustfs_crypto::Error::ErrInvalidKeyLength)),
-            Error::Io(std::io::Error::other("io payload")),
-            Error::StringError("plain".to_string()),
-            Error::NoSuchUser("u".to_string()),
-            Error::ConfigNotFound,
-        ];
-
-        for error in errors {
-            let cloned = error.clone();
-            assert_eq!(
-                std::mem::discriminant(&error),
-                std::mem::discriminant(&cloned),
-                "clone must keep the variant of {error:?}"
-            );
-            assert_eq!(error.to_string(), cloned.to_string(), "clone must keep the rendered message");
-        }
-    }
-
    #[test]
    fn test_error_display_format() {
        let test_cases = vec![
@@ -5,13 +5,6 @@ All notable changes to the rustfs-io-core and rustfs-io-metrics crates will be d
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

-## [Unreleased]
-
-### Removed
-
-#### rustfs-io-metrics
- **Unified configuration** (added in 0.0.5): the zero-consumer `IoConfig`, `CacheSettings`, `IoSchedulerSettings`, `BackpressureSettings`, `TimeoutSettings`, `DeadlockDetectionSettings` types and their `DEFAULT_*` constants were removed (rustfs/rustfs#6008); rustfs-io-core's `IoSchedulerConfig`/`BackpressureConfig` remain the canonical configuration types.
-
 ## [0.0.5] - 2025-01-XX

 ### Added
@@ -33,23 +33,31 @@ default = []
 hotpath = [
    "hotpath/hotpath",
    "hotpath/tokio",
+    "rustfs-common/hotpath",
    "rustfs-s3-ops/hotpath",
+    "rustfs-utils/hotpath",
 ]
 hotpath-alloc = [
    "hotpath",
    "hotpath/hotpath-alloc",
+    "rustfs-common/hotpath-alloc",
    "rustfs-s3-ops/hotpath-alloc",
+    "rustfs-utils/hotpath-alloc",
 ]
 hotpath-cpu = [
    "hotpath",
    "hotpath/hotpath-cpu",
+    "rustfs-common/hotpath-cpu",
    "rustfs-s3-ops/hotpath-cpu",
+    "rustfs-utils/hotpath-cpu",
 ]

 [dependencies]
 hotpath.workspace = true
 metrics = { workspace = true }
+rustfs-common = { workspace = true }
 rustfs-s3-ops = { workspace = true }
+rustfs-utils = { workspace = true, features = ["ip"] }
 num_cpus = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true, features = ["sync", "fs", "rt-multi-thread"] }
@@ -27,6 +27,7 @@
 - **Metrics Collection**: Unified metrics recording and reporting
 - **Bandwidth Monitoring**: Real-time bandwidth observation and analysis
 - **Performance Metrics**: I/O performance metrics collection
+- **Unified Configuration**: Centralized configuration management
 - **Exporter Boundary**: Emit via `metrics`, export via `rustfs-obs`, no Prometheus HTTP endpoint

 ## Features
@@ -202,6 +203,30 @@ path and include:
 deltas with `operation` and `backend` columns, so the TCP baseline can attribute
 bytes and request/error counts to `tcp-http` transport operations.

+### Unified Configuration
+
+Centralized configuration management:
+
+```rust
+use rustfs_io_metrics::{
+    IoConfig, CacheSettings, IoSchedulerSettings,
+    BackpressureSettings, TimeoutSettings,
+};
+
+let config = IoConfig::new()
+    .with_cache(CacheSettings::new()
+        .with_max_capacity(10_000)
+        .with_ttl(std::time::Duration::from_secs(300)))
+    .with_scheduler(IoSchedulerSettings::new()
+        .with_max_concurrent_reads(64))
+    .with_backpressure(BackpressureSettings::new())
+    .with_timeout(TimeoutSettings::new());
+
+// Access configuration
+println!("Cache capacity: {}", config.cache.max_capacity);
+println!("Max concurrent reads: {}", config.scheduler.max_concurrent_reads);
+```
+
 ## Module Structure

 ```
@@ -210,6 +235,7 @@ rustfs-io-metrics/
 │   ├── lib.rs               # Module entry
 │   ├── cache_config.rs      # Cache configuration
 │   ├── adaptive_ttl.rs      # Adaptive TTL
+│   ├── config.rs            # Unified configuration
 │   ├── io_metrics.rs        # I/O metrics
 │   ├── backpressure_metrics.rs # Backpressure metrics
 │   ├── deadlock_metrics.rs  # Deadlock metrics
@@ -252,6 +278,7 @@ Useful source references:

 - [Crate API overview](./src/lib.rs)
 - [Metrics example](./examples/metrics_example.rs)
+- [Configuration module](./src/config.rs)
 - [Adaptive TTL module](./src/adaptive_ttl.rs)

 ## Related Modules
@@ -27,6 +27,7 @@
 - **指标收集**：统一的指标记录和上报
 - **带宽监控**：实时带宽观测和分析
 - **性能指标**：I/O 性能指标收集
+- **统一配置**：集中式配置管理
 - **导出边界**：通过 `metrics` 主动上报，由 `rustfs-obs` 负责 OTEL 导出，不提供 Prometheus HTTP 端点

 ## ✨ 核心功能
@@ -171,6 +172,30 @@ println!("读取速率: {} bytes/s", snapshot.read_bytes_per_sec);
 println!("写入速率: {} bytes/s", snapshot.write_bytes_per_sec);
 ```

+### 统一配置 (IoConfig)
+
+集中式配置管理：
+
+```rust
+use rustfs_io_metrics::{
+    IoConfig, CacheSettings, IoSchedulerSettings,
+    BackpressureSettings, TimeoutSettings,
+};
+
+let config = IoConfig::new()
+    .with_cache(CacheSettings::new()
+        .with_max_capacity(10_000)
+        .with_ttl(std::time::Duration::from_secs(300)))
+    .with_scheduler(IoSchedulerSettings::new()
+        .with_max_concurrent_reads(64))
+    .with_backpressure(BackpressureSettings::new())
+    .with_timeout(TimeoutSettings::new());
+
+// 访问配置
+println!("缓存容量: {}", config.cache.max_capacity);
+println!("最大并发读: {}", config.scheduler.max_concurrent_reads);
+```
+
 ## 📊 指标类型

 ### I/O 调度指标
@@ -208,6 +233,21 @@ println!("写入速率: {} bytes/s", snapshot.write_bytes_per_sec);
 | `operation_duration_secs` | 操作时长 | Histogram |
 | `operation_progress` | 操作进度 | Gauge |

+## 🔧 配置
+
+### 代码配置
+
+```rust
+use rustfs_io_metrics::{CacheSettings, IoConfig};
+
+let settings = CacheSettings::new()
+    .with_max_capacity(5000)
+    .with_ttl(std::time::Duration::from_secs(600))
+    .with_max_memory(200 * 1024 * 1024);
+
+let config = IoConfig::new().with_cache(settings);
+```
+
 ## 📁 模块结构

 ```
@@ -216,6 +256,7 @@ rustfs-io-metrics/
 │   ├── lib.rs               # 模块入口
 │   ├── cache_config.rs      # 缓存配置
 │   ├── adaptive_ttl.rs      # 自适应 TTL
+│   ├── config.rs            # 统一配置
 │   ├── io_metrics.rs        # I/O 指标
 │   ├── backpressure_metrics.rs # 背压指标
 │   ├── deadlock_metrics.rs  # 死锁指标
@@ -256,6 +297,7 @@ cargo doc --package rustfs-io-metrics --no-deps --open

 - [Crate API 概览](./src/lib.rs)
 - [指标示例](./examples/metrics_example.rs)
+- [配置模块](./src/config.rs)
 - [自适应 TTL 模块](./src/adaptive_ttl.rs)

 ## 🔗 相关模块
@@ -14,7 +14,9 @@

 //! Example demonstrating metrics and configuration usage.

-use rustfs_io_metrics::{AccessTracker, AdaptiveTTL, CacheConfig, record_cache_size};
+use rustfs_io_metrics::{
+    AccessTracker, AdaptiveTTL, CacheConfig, CacheSettings, IoConfig, IoSchedulerSettings, record_cache_size,
+};
 use std::time::Duration;

 fn main() {
@@ -29,7 +31,10 @@ fn main() {
    // 3. Access tracking example
    access_tracker_example();

-    // 4. Metrics recording example
+    // 4. Unified configuration example
+    unified_config_example();
+
+    // 5. Metrics recording example
    metrics_recording_example();
 }

@@ -104,6 +109,26 @@ fn access_tracker_example() {
    println!();
 }

+fn unified_config_example() {
+    println!("--- Unified Configuration ---");
+
+    let config = IoConfig::new()
+        .with_cache(
+            CacheSettings::new()
+                .with_max_capacity(5000)
+                .with_ttl(Duration::from_secs(600)),
+        )
+        .with_scheduler(IoSchedulerSettings::new().with_max_concurrent_reads(64));
+
+    println!("  Cache capacity: {}", config.cache.max_capacity);
+    println!("  Cache TTL: {:?}", config.cache.default_ttl);
+    println!("  Max concurrent reads: {}", config.scheduler.max_concurrent_reads);
+    println!("  Backpressure high watermark: {}", config.backpressure.high_watermark);
+    println!("  Default timeout: {:?}", config.timeout.default_timeout);
+
+    println!();
+}
+
 fn metrics_recording_example() {
    println!("--- Metrics Recording ---");

@@ -315,44 +315,6 @@ impl Default for AccessTracker {
 mod tests {
    use super::*;

-    /// Replaces the per-helper smoke tests that called the record_* helpers
-    /// and asserted nothing: the calls (same literals) now run against a local
-    /// DebuggingRecorder and every metric name the helpers own must actually
-    /// be emitted (rustfs/backlog#1836 PR3).
-    #[test]
-    fn record_helpers_emit_their_metrics() {
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-        metrics::with_local_recorder(&recorder, || {
-            record_ttl_adjustment("test-key", 100, 150);
-            record_ttl_adjustment("test-key", 100, 50);
-            record_ttl_expiration();
-            record_early_eviction("cold");
-            record_early_eviction("low_priority");
-            record_access_pattern_change("sequential", "random");
-            record_access_pattern_change("random", "sequential");
-        });
-
-        let emitted: std::collections::HashSet<String> = snapshotter
-            .snapshot()
-            .into_vec()
-            .into_iter()
-            .map(|(composite, _, _, _)| composite.key().name().to_string())
-            .collect();
-        for expected in [
-            "rustfs_cache_ttl_adjustments",
-            "rustfs_cache_ttl_base",
-            "rustfs_cache_ttl_adjusted",
-            "rustfs_cache_ttl_extensions",
-            "rustfs_cache_ttl_reductions",
-            "rustfs_cache_ttl_expirations",
-            "rustfs_cache_evictions_early",
-            "rustfs_cache_access_pattern_changes",
-        ] {
-            assert!(emitted.contains(expected), "{expected} must be emitted by its record helper");
-        }
-    }
-
    #[test]
    fn test_adaptive_ttl_stats() {
        let mut stats = AdaptiveTTLStats::new();
@@ -373,6 +335,30 @@ mod tests {
        assert!((stats.reduction_rate() - 0.3333333333333333).abs() < 0.01);
    }

+    #[test]
+    fn test_record_ttl_adjustment() {
+        // This test verifies the function compiles and runs
+        record_ttl_adjustment("test-key", 100, 150);
+        record_ttl_adjustment("test-key", 100, 50);
+    }
+
+    #[test]
+    fn test_record_ttl_expiration() {
+        record_ttl_expiration();
+    }
+
+    #[test]
+    fn test_record_early_eviction() {
+        record_early_eviction("cold");
+        record_early_eviction("low_priority");
+    }
+
+    #[test]
+    fn test_record_access_pattern_change() {
+        record_access_pattern_change("sequential", "random");
+        record_access_pattern_change("random", "sequential");
+    }
+
    #[test]
    fn test_access_record() {
        let mut record = AccessRecord::new();
@@ -53,38 +53,30 @@ pub fn record_backpressure_deactivation() {
 mod tests {
    use super::*;

-    /// Replaces the per-helper smoke tests that called the record_* helpers
-    /// and asserted nothing: the calls (same literals) now run against a local
-    /// DebuggingRecorder and every metric name the helpers own must actually
-    /// be emitted (rustfs/backlog#1836 PR3).
    #[test]
-    fn record_helpers_emit_their_metrics() {
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-        metrics::with_local_recorder(&recorder, || {
-            record_backpressure_state_change("normal", "warning");
-            record_backpressure_state_change("warning", "critical");
-            record_backpressure_rejection();
-            record_concurrent_operations(10);
-            record_concurrent_operations(32);
-            record_backpressure_activation();
-            record_backpressure_deactivation();
-        });
+    fn test_record_backpressure_state_change() {
+        record_backpressure_state_change("normal", "warning");
+        record_backpressure_state_change("warning", "critical");
+    }

-        let emitted: std::collections::HashSet<String> = snapshotter
-            .snapshot()
-            .into_vec()
-            .into_iter()
-            .map(|(composite, _, _, _)| composite.key().name().to_string())
-            .collect();
-        for expected in [
-            "rustfs_backpressure_state_changes",
-            "rustfs_backpressure_rejections",
-            "rustfs_backpressure_concurrent",
-            "rustfs_backpressure_activations",
-            "rustfs_backpressure_deactivations",
-        ] {
-            assert!(emitted.contains(expected), "{expected} must be emitted by its record helper");
-        }
+    #[test]
+    fn test_record_backpressure_rejection() {
+        record_backpressure_rejection();
+    }
+
+    #[test]
+    fn test_record_concurrent_operations() {
+        record_concurrent_operations(10);
+        record_concurrent_operations(32);
+    }
+
+    #[test]
+    fn test_record_backpressure_activation() {
+        record_backpressure_activation();
+    }
+
+    #[test]
+    fn test_record_backpressure_deactivation() {
+        record_backpressure_deactivation();
    }
 }
@@ -0,0 +1,391 @@
+// Copyright 2024 RustFS Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Unified configuration interface for I/O operations.
+//!
+//! This module provides a centralized configuration interface
+//! for all I/O-related settings.
+
+use std::time::Duration;
+
+// ============================================================================
+// Configuration Constants
+// ============================================================================
+
+/// Default cache max capacity.
+pub const DEFAULT_CACHE_MAX_CAPACITY: u64 = 10_000;
+/// Default cache TTL in seconds.
+pub const DEFAULT_CACHE_TTL_SECS: u64 = 300;
+/// Default cache max memory in bytes (100 MB).
+pub const DEFAULT_CACHE_MAX_MEMORY: u64 = 100 * 1024 * 1024;
+
+/// Default I/O scheduler max concurrent reads.
+pub const DEFAULT_MAX_CONCURRENT_READS: usize = 32;
+/// Default high priority size threshold (64 KB).
+pub const DEFAULT_HIGH_PRIORITY_SIZE_THRESHOLD: usize = 64 * 1024;
+/// Default low priority size threshold (4 MB).
+pub const DEFAULT_LOW_PRIORITY_SIZE_THRESHOLD: usize = 4 * 1024 * 1024;
+
+/// Default backpressure high watermark.
+pub const DEFAULT_BACKPRESSURE_HIGH_WATERMARK: f64 = 0.8;
+/// Default backpressure low watermark.
+pub const DEFAULT_BACKPRESSURE_LOW_WATERMARK: f64 = 0.5;
+
+/// Default lock acquire timeout in seconds.
+pub const DEFAULT_LOCK_ACQUIRE_TIMEOUT_SECS: u64 = 5;
+/// Default deadlock detection interval in seconds.
+pub const DEFAULT_DEADLOCK_DETECTION_INTERVAL_SECS: u64 = 1;
+
+/// Default base buffer size (128 KB).
+pub const DEFAULT_BASE_BUFFER_SIZE: usize = 128 * 1024;
+/// Default max buffer size (1 MB).
+pub const DEFAULT_MAX_BUFFER_SIZE: usize = 1024 * 1024;
+/// Default min buffer size (4 KB).
+pub const DEFAULT_MIN_BUFFER_SIZE: usize = 4 * 1024;
+
+// ============================================================================
+// Cache Configuration
+// ============================================================================
+
+/// Cache configuration settings.
+#[derive(Debug, Clone)]
+pub struct CacheSettings {
+    /// Maximum cache capacity.
+    pub max_capacity: u64,
+    /// Default TTL.
+    pub default_ttl: Duration,
+    /// Maximum memory usage.
+    pub max_memory: u64,
+    /// Whether adaptive TTL is enabled.
+    pub adaptive_ttl_enabled: bool,
+}
+
+impl Default for CacheSettings {
+    fn default() -> Self {
+        Self {
+            max_capacity: DEFAULT_CACHE_MAX_CAPACITY,
+            default_ttl: Duration::from_secs(DEFAULT_CACHE_TTL_SECS),
+            max_memory: DEFAULT_CACHE_MAX_MEMORY,
+            adaptive_ttl_enabled: true,
+        }
+    }
+}
+
+impl CacheSettings {
+    /// Create new cache settings.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Builder: set max capacity.
+    pub fn with_max_capacity(mut self, capacity: u64) -> Self {
+        self.max_capacity = capacity;
+        self
+    }
+
+    /// Builder: set TTL.
+    pub fn with_ttl(mut self, ttl: Duration) -> Self {
+        self.default_ttl = ttl;
+        self
+    }
+
+    /// Builder: set max memory.
+    pub fn with_max_memory(mut self, memory: u64) -> Self {
+        self.max_memory = memory;
+        self
+    }
+}
+
+// ============================================================================
+// I/O Scheduler Configuration
+// ============================================================================
+
+/// I/O scheduler configuration settings.
+#[derive(Debug, Clone)]
+pub struct IoSchedulerSettings {
+    /// Maximum concurrent reads.
+    pub max_concurrent_reads: usize,
+    /// High priority size threshold.
+    pub high_priority_threshold: usize,
+    /// Low priority size threshold.
+    pub low_priority_threshold: usize,
+    /// Base buffer size.
+    pub base_buffer_size: usize,
+    /// Max buffer size.
+    pub max_buffer_size: usize,
+    /// Min buffer size.
+    pub min_buffer_size: usize,
+    /// Whether priority scheduling is enabled.
+    pub priority_enabled: bool,
+}
+
+impl Default for IoSchedulerSettings {
+    fn default() -> Self {
+        Self {
+            max_concurrent_reads: DEFAULT_MAX_CONCURRENT_READS,
+            high_priority_threshold: DEFAULT_HIGH_PRIORITY_SIZE_THRESHOLD,
+            low_priority_threshold: DEFAULT_LOW_PRIORITY_SIZE_THRESHOLD,
+            base_buffer_size: DEFAULT_BASE_BUFFER_SIZE,
+            max_buffer_size: DEFAULT_MAX_BUFFER_SIZE,
+            min_buffer_size: DEFAULT_MIN_BUFFER_SIZE,
+            priority_enabled: true,
+        }
+    }
+}
+
+impl IoSchedulerSettings {
+    /// Create new settings.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Builder: set max concurrent reads.
+    pub fn with_max_concurrent_reads(mut self, max: usize) -> Self {
+        self.max_concurrent_reads = max;
+        self
+    }
+
+    /// Builder: set buffer sizes.
+    pub fn with_buffer_sizes(mut self, base: usize, min: usize, max: usize) -> Self {
+        self.base_buffer_size = base;
+        self.min_buffer_size = min;
+        self.max_buffer_size = max;
+        self
+    }
+}
+
+// ============================================================================
+// Backpressure Configuration
+// ============================================================================
+
+/// Backpressure configuration settings.
+#[derive(Debug, Clone)]
+pub struct BackpressureSettings {
+    /// Whether backpressure is enabled.
+    pub enabled: bool,
+    /// High watermark (percentage).
+    pub high_watermark: f64,
+    /// Low watermark (percentage).
+    pub low_watermark: f64,
+    /// Cooldown duration.
+    pub cooldown: Duration,
+}
+
+impl Default for BackpressureSettings {
+    fn default() -> Self {
+        Self {
+            enabled: true,
+            high_watermark: DEFAULT_BACKPRESSURE_HIGH_WATERMARK,
+            low_watermark: DEFAULT_BACKPRESSURE_LOW_WATERMARK,
+            cooldown: Duration::from_millis(100),
+        }
+    }
+}
+
+impl BackpressureSettings {
+    /// Create new settings.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Get high watermark threshold for a given max value.
+    pub fn high_threshold(&self, max: usize) -> usize {
+        (max as f64 * self.high_watermark) as usize
+    }
+
+    /// Get low watermark threshold for a given max value.
+    pub fn low_threshold(&self, max: usize) -> usize {
+        (max as f64 * self.low_watermark) as usize
+    }
+}
+
+// ============================================================================
+// Timeout Configuration
+// ============================================================================
+
+/// Timeout configuration settings.
+#[derive(Debug, Clone)]
+pub struct TimeoutSettings {
+    /// Default operation timeout.
+    pub default_timeout: Duration,
+    /// Maximum retries.
+    pub max_retries: usize,
+    /// Retry backoff factor.
+    pub retry_backoff_factor: f64,
+    /// Lock acquire timeout.
+    pub lock_acquire_timeout: Duration,
+}
+
+impl Default for TimeoutSettings {
+    fn default() -> Self {
+        Self {
+            default_timeout: Duration::from_secs(30),
+            max_retries: 3,
+            retry_backoff_factor: 2.0,
+            lock_acquire_timeout: Duration::from_secs(DEFAULT_LOCK_ACQUIRE_TIMEOUT_SECS),
+        }
+    }
+}
+
+impl TimeoutSettings {
+    /// Create new settings.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Calculate timeout with backoff for a given retry count.
+    pub fn timeout_with_backoff(&self, retry_count: usize) -> Duration {
+        let multiplier = self.retry_backoff_factor.powi(retry_count as i32);
+        Duration::from_secs_f64(self.default_timeout.as_secs_f64() * multiplier)
+    }
+}
+
+// ============================================================================
+// Deadlock Detection Configuration
+// ============================================================================
+
+/// Deadlock detection configuration settings.
+#[derive(Debug, Clone)]
+pub struct DeadlockDetectionSettings {
+    /// Whether detection is enabled.
+    pub enabled: bool,
+    /// Detection interval.
+    pub detection_interval: Duration,
+    /// Maximum lock hold time before warning.
+    pub max_hold_time: Duration,
+}
+
+impl Default for DeadlockDetectionSettings {
+    fn default() -> Self {
+        Self {
+            enabled: true,
+            detection_interval: Duration::from_secs(DEFAULT_DEADLOCK_DETECTION_INTERVAL_SECS),
+            max_hold_time: Duration::from_secs(30),
+        }
+    }
+}
+
+impl DeadlockDetectionSettings {
+    /// Create new settings.
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+// ============================================================================
+// Unified Configuration
+// ============================================================================
+
+/// Unified configuration for all I/O operations.
+#[derive(Debug, Clone, Default)]
+pub struct IoConfig {
+    /// Cache settings.
+    pub cache: CacheSettings,
+    /// I/O scheduler settings.
+    pub scheduler: IoSchedulerSettings,
+    /// Backpressure settings.
+    pub backpressure: BackpressureSettings,
+    /// Timeout settings.
+    pub timeout: TimeoutSettings,
+    /// Deadlock detection settings.
+    pub deadlock_detection: DeadlockDetectionSettings,
+}
+
+impl IoConfig {
+    /// Create new unified configuration.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Builder: set cache settings.
+    pub fn with_cache(mut self, cache: CacheSettings) -> Self {
+        self.cache = cache;
+        self
+    }
+
+    /// Builder: set scheduler settings.
+    pub fn with_scheduler(mut self, scheduler: IoSchedulerSettings) -> Self {
+        self.scheduler = scheduler;
+        self
+    }
+
+    /// Builder: set backpressure settings.
+    pub fn with_backpressure(mut self, backpressure: BackpressureSettings) -> Self {
+        self.backpressure = backpressure;
+        self
+    }
+
+    /// Builder: set timeout settings.
+    pub fn with_timeout(mut self, timeout: TimeoutSettings) -> Self {
+        self.timeout = timeout;
+        self
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_cache_settings() {
+        let settings = CacheSettings::new()
+            .with_max_capacity(5000)
+            .with_ttl(Duration::from_secs(600));
+
+        assert_eq!(settings.max_capacity, 5000);
+        assert_eq!(settings.default_ttl, Duration::from_secs(600));
+    }
+
+    #[test]
+    fn test_io_scheduler_settings() {
+        let settings =
+            IoSchedulerSettings::new()
+                .with_max_concurrent_reads(64)
+                .with_buffer_sizes(256 * 1024, 8 * 1024, 2 * 1024 * 1024);
+
+        assert_eq!(settings.max_concurrent_reads, 64);
+        assert_eq!(settings.base_buffer_size, 256 * 1024);
+    }
+
+    #[test]
+    fn test_backpressure_settings() {
+        let settings = BackpressureSettings::new();
+
+        assert_eq!(settings.high_threshold(100), 80);
+        assert_eq!(settings.low_threshold(100), 50);
+    }
+
+    #[test]
+    fn test_timeout_settings() {
+        let settings = TimeoutSettings::new();
+
+        // First retry: 30s * 2 = 60s
+        let timeout1 = settings.timeout_with_backoff(1);
+        assert!(timeout1.as_secs() >= 60);
+
+        // Second retry: 30s * 4 = 120s
+        let timeout2 = settings.timeout_with_backoff(2);
+        assert!(timeout2.as_secs() >= 120);
+    }
+
+    #[test]
+    fn test_unified_config() {
+        let config = IoConfig::new()
+            .with_cache(CacheSettings::new().with_max_capacity(5000))
+            .with_scheduler(IoSchedulerSettings::new().with_max_concurrent_reads(64));
+
+        assert_eq!(config.cache.max_capacity, 5000);
+        assert_eq!(config.scheduler.max_concurrent_reads, 64);
+    }
+}
@@ -72,48 +72,39 @@ pub fn record_wait_edge_removed() {
 mod tests {
    use super::*;

-    /// Replaces the per-helper smoke tests that called the record_* helpers
-    /// and asserted nothing: the calls (same literals) now run against a local
-    /// DebuggingRecorder and every metric name the helpers own must actually
-    /// be emitted (rustfs/backlog#1836 PR3).
    #[test]
-    fn record_helpers_emit_their_metrics() {
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-        metrics::with_local_recorder(&recorder, || {
-            record_deadlock_detected(3);
-            record_deadlock_detected(5);
-            record_long_held_lock(1, Duration::from_secs(30));
-            record_long_held_lock(2, Duration::from_secs(60));
-            record_lock_acquisition("mutex");
-            record_lock_acquisition("rwlock");
-            record_lock_release("mutex", Duration::from_millis(10));
-            record_lock_release("rwlock", Duration::from_millis(5));
-            record_lock_contention("mutex");
-            record_lock_contention("rwlock");
-            record_wait_edge_added();
-            record_wait_edge_removed();
-        });
+    fn test_record_deadlock_detected() {
+        record_deadlock_detected(3);
+        record_deadlock_detected(5);
+    }

-        let emitted: std::collections::HashSet<String> = snapshotter
-            .snapshot()
-            .into_vec()
-            .into_iter()
-            .map(|(composite, _, _, _)| composite.key().name().to_string())
-            .collect();
-        for expected in [
-            "rustfs_deadlock_detected_total",
-            "rustfs_deadlock_cycle_length",
-            "rustfs_deadlock_long_held",
-            "rustfs_deadlock_hold_time_secs",
-            "rustfs_lock_acquisitions",
-            "rustfs_lock_releases",
-            "rustfs_lock_hold_time_secs",
-            "rustfs_lock_contentions",
-            "rustfs_deadlock_wait_edges_added",
-            "rustfs_deadlock_wait_edges_removed",
-        ] {
-            assert!(emitted.contains(expected), "{expected} must be emitted by its record helper");
-        }
+    #[test]
+    fn test_record_long_held_lock() {
+        record_long_held_lock(1, Duration::from_secs(30));
+        record_long_held_lock(2, Duration::from_secs(60));
+    }
+
+    #[test]
+    fn test_record_lock_acquisition() {
+        record_lock_acquisition("mutex");
+        record_lock_acquisition("rwlock");
+    }
+
+    #[test]
+    fn test_record_lock_release() {
+        record_lock_release("mutex", Duration::from_millis(10));
+        record_lock_release("rwlock", Duration::from_millis(5));
+    }
+
+    #[test]
+    fn test_record_lock_contention() {
+        record_lock_contention("mutex");
+        record_lock_contention("rwlock");
+    }
+
+    #[test]
+    fn test_record_wait_edge() {
+        record_wait_edge_added();
+        record_wait_edge_removed();
    }
 }
@@ -196,19 +196,22 @@ pub const INTERNODE_OPERATION_METRICS: &[InternodeOperationMetricDescriptor] = &
    },
 ];

-static STABLE_SERVER_LABEL: OnceLock<String> = OnceLock::new();
-
-/// Injects the stable server label (node name or address) stamped on
-/// internode metrics. The runtime calls this when the local node name is
-/// published (see ecstore's `set_local_node_name`); the first write wins.
-/// io-metrics is a leaf crate and no longer resolves node identity itself
-/// (backlog#1834) — before injection the label reads "unset".
-pub fn set_internode_server_label(label: impl Into<String>) {
-    let _ = STABLE_SERVER_LABEL.set(label.into());
-}
-
 fn current_server_label() -> &'static str {
-    STABLE_SERVER_LABEL.get().map(String::as_str).unwrap_or("unset")
+    static STABLE_SERVER_LABEL: OnceLock<String> = OnceLock::new();
+    static FALLBACK_SERVER_LABEL: LazyLock<String> = LazyLock::new(rustfs_utils::get_local_ip_with_default);
+
+    if let Some(server) = STABLE_SERVER_LABEL.get() {
+        return server.as_str();
+    }
+
+    if let Some(server) = rustfs_common::try_get_global_local_node_name() {
+        let _ = STABLE_SERVER_LABEL.set(server);
+        if let Some(server) = STABLE_SERVER_LABEL.get() {
+            return server.as_str();
+        }
+    }
+
+    FALLBACK_SERVER_LABEL.as_str()
 }

 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
@@ -169,58 +169,46 @@ impl IoSchedulerStats {
 mod tests {
    use super::*;

-    /// Replaces the per-helper smoke tests that called the record_* helpers
-    /// and asserted nothing: the calls (same literals) now run against a local
-    /// DebuggingRecorder and every metric name the helpers own must actually
-    /// be emitted (rustfs/backlog#1836 PR3).
    #[test]
-    fn record_helpers_emit_their_metrics() {
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-        metrics::with_local_recorder(&recorder, || {
-            record_io_scheduler_decision(128 * 1024, "low", "sequential");
-            record_io_scheduler_decision(64 * 1024, "high", "random");
-            record_io_priority_decision("high", 1024);
-            record_io_priority_decision("normal", 1024 * 1024);
-            record_io_priority_decision("low", 10 * 1024 * 1024);
-            record_load_level_change("low", "medium");
-            record_load_level_change("medium", "high");
-            record_bandwidth_observation(100 * 1024 * 1024);
-            record_bandwidth_observation(500 * 1024 * 1024);
-            record_buffer_size_adjustment(128 * 1024, 64 * 1024, "concurrency");
-            record_buffer_size_adjustment(128 * 1024, 256 * 1024, "sequential");
-            record_queue_operation("enqueue", "high", 10);
-            record_queue_operation("dequeue", "high", 9);
-            record_starvation_event("low");
-        });
+    fn test_record_io_scheduler_decision() {
+        record_io_scheduler_decision(128 * 1024, "low", "sequential");
+        record_io_scheduler_decision(64 * 1024, "high", "random");
+    }

-        let emitted: std::collections::HashSet<String> = snapshotter
-            .snapshot()
-            .into_vec()
-            .into_iter()
-            .map(|(composite, _, _, _)| composite.key().name().to_string())
-            .collect();
-        for expected in [
-            "rustfs_io_scheduler_decisions",
-            "rustfs_io_scheduler_buffer_size",
-            "rustfs_io_scheduler_load",
-            "rustfs_io_scheduler_strategy",
-            "rustfs_io_scheduler_buffer_size_histogram",
-            "rustfs_io_priority_decisions",
-            "rustfs_io_priority_by_level",
-            "rustfs_io_priority_request_size",
-            "rustfs_io_load_changes",
-            "rustfs_io_bandwidth_bps",
-            "rustfs_io_bandwidth_histogram",
-            "rustfs_io_buffer_adjustments",
-            "rustfs_io_buffer_original",
-            "rustfs_io_buffer_adjusted",
-            "rustfs_io_queue_operations",
-            "rustfs_io_queue_size",
-            "rustfs_io_starvation_events",
-        ] {
-            assert!(emitted.contains(expected), "{expected} must be emitted by its record helper");
-        }
+    #[test]
+    fn test_record_io_priority_decision() {
+        record_io_priority_decision("high", 1024);
+        record_io_priority_decision("normal", 1024 * 1024);
+        record_io_priority_decision("low", 10 * 1024 * 1024);
+    }
+
+    #[test]
+    fn test_record_load_level_change() {
+        record_load_level_change("low", "medium");
+        record_load_level_change("medium", "high");
+    }
+
+    #[test]
+    fn test_record_bandwidth_observation() {
+        record_bandwidth_observation(100 * 1024 * 1024);
+        record_bandwidth_observation(500 * 1024 * 1024);
+    }
+
+    #[test]
+    fn test_record_buffer_size_adjustment() {
+        record_buffer_size_adjustment(128 * 1024, 64 * 1024, "concurrency");
+        record_buffer_size_adjustment(128 * 1024, 256 * 1024, "sequential");
+    }
+
+    #[test]
+    fn test_record_queue_operation() {
+        record_queue_operation("enqueue", "high", 10);
+        record_queue_operation("dequeue", "high", 9);
+    }
+
+    #[test]
+    fn test_record_starvation_event() {
+        record_starvation_event("low");
    }

    #[test]
@@ -58,7 +58,7 @@ use std::sync::{
 /// When `false`, `record_put_object_path` and `record_put_object_stage_duration`
 /// become no-ops, and callers can skip the `Instant::now()` syscalls entirely.
 ///
-/// Enabled only through an explicit runtime opt-in.
+/// Set to `true` during startup when OTEL metric export is enabled.
 static PUT_STAGE_METRICS_ENABLED: AtomicBool = AtomicBool::new(false);
 static GET_STAGE_METRICS_ENABLED: AtomicBool = AtomicBool::new(false);

@@ -78,7 +78,7 @@ static METRICS_ENABLED: AtomicBool = AtomicBool::new(false);

 /// Enable or disable detailed per-stage PUT metrics.
 ///
-/// Called once during startup after applying the detailed PUT attribution opt-in.
+/// Called once during startup, typically gated by `rustfs_obs::observability_metric_enabled()`.
 pub fn set_put_stage_metrics_enabled(enabled: bool) {
    PUT_STAGE_METRICS_ENABLED.store(enabled, Ordering::Relaxed);
 }
@@ -103,12 +103,6 @@ pub fn put_stage_metrics_enabled() -> bool {
    PUT_STAGE_METRICS_ENABLED.load(Ordering::Relaxed)
 }

-/// Start a PUT-stage timer only when detailed PUT attribution is enabled.
-#[inline(always)]
-pub fn put_stage_timer() -> Option<std::time::Instant> {
-    put_stage_metrics_enabled().then(std::time::Instant::now)
-}
-
 #[inline(always)]
 pub fn get_stage_metrics_enabled() -> bool {
    GET_STAGE_METRICS_ENABLED.load(Ordering::Relaxed)
@@ -179,6 +173,7 @@ pub mod backpressure_metrics;
 pub mod cache_config;
 pub mod capacity_metrics;
 pub mod collector;
+pub mod config;
 pub mod deadlock_metrics;
 pub mod internode_metrics;
 pub mod io_metrics;
@@ -265,6 +260,13 @@ pub use timeout_metrics::{
    record_operation_progress, record_stalled_operation, record_timeout_event,
 };

+// Config exports
+pub use config::{
+    BackpressureSettings, CacheSettings, DEFAULT_BASE_BUFFER_SIZE, DEFAULT_CACHE_MAX_CAPACITY, DEFAULT_CACHE_MAX_MEMORY,
+    DEFAULT_CACHE_TTL_SECS, DEFAULT_MAX_BUFFER_SIZE, DEFAULT_MAX_CONCURRENT_READS, DEFAULT_MIN_BUFFER_SIZE,
+    DeadlockDetectionSettings, IoConfig, IoSchedulerSettings, TimeoutSettings,
+};
+
 // Re-exports for convenience
 pub use collector::MetricsCollector;
 pub use performance::PerformanceMetrics;
@@ -440,7 +442,7 @@ pub fn record_get_object_request_result(status: &str, duration_secs: f64) {
 /// Record PutObject request start.
 #[inline(always)]
 pub fn record_put_object_request_start(concurrent_requests: usize) {
-    if !metrics_enabled() {
+    if !put_stage_metrics_enabled() {
        return;
    }
    counter!("rustfs_io_put_object_requests_total").increment(1);
@@ -450,7 +452,7 @@ pub fn record_put_object_request_start(concurrent_requests: usize) {
 /// Record PutObject request result.
 #[inline(always)]
 pub fn record_put_object_request_result(status: &str, duration_secs: f64) {
-    if !metrics_enabled() {
+    if !put_stage_metrics_enabled() {
        return;
    }
    counter!("rustfs_io_put_object_request_results_total", "status" => status.to_string()).increment(1);
@@ -812,17 +814,6 @@ pub fn record_get_object_metadata_fanout_shape(path: &'static str, total: usize,
        .record(metadata_fanout_count_to_f64(non_valid));
 }

-/// Record task lifecycle shape for one GetObject metadata fanout.
-#[inline(always)]
-pub fn record_get_object_metadata_fanout_lifecycle(path: &'static str, scheduled: usize, completed: usize, cancelled: usize) {
-    if !get_stage_metrics_enabled() {
-        return;
-    }
-    histogram!("rustfs_io_get_object_metadata_fanout_scheduled", "path" => path).record(metadata_fanout_count_to_f64(scheduled));
-    histogram!("rustfs_io_get_object_metadata_fanout_completed", "path" => path).record(metadata_fanout_count_to_f64(completed));
-    histogram!("rustfs_io_get_object_metadata_fanout_cancelled", "path" => path).record(metadata_fanout_count_to_f64(cancelled));
-}
-
 /// Record a guarded metadata early-stop hit for GetObject.
 #[inline(always)]
 pub fn record_get_object_metadata_early_stop_hit(path: &'static str, reason: &'static str) {
@@ -1922,7 +1913,7 @@ pub fn record_get_object(duration_ms: f64, size_bytes: i64) {
 /// * `zero_copy_eligible` - Whether the request was eligible for a zero-copy path
 #[inline(always)]
 pub fn record_put_object(duration_ms: f64, size_bytes: i64, zero_copy_eligible: bool) {
-    if !metrics_enabled() {
+    if !put_stage_metrics_enabled() {
        return;
    }
    counter!("rustfs_s3_put_object_total").increment(1);
@@ -2021,13 +2012,6 @@ pub fn record_put_object_stage_duration(stage: &'static str, duration_ms: f64) {
    histogram!("rustfs_s3_put_object_stage_duration_ms", "stage" => stage).record(duration_ms);
 }

-#[inline(always)]
-pub fn record_put_object_stage_duration_from(stage: &'static str, started_at: Option<std::time::Instant>) {
-    if let Some(started_at) = started_at {
-        record_put_object_stage_duration(stage, started_at.elapsed().as_secs_f64() * 1000.0);
-    }
-}
-
 /// Record generic internal operation stage duration (non-PUT paths).
 /// Use this for metacache walks, listing, lifecycle, and other background
 /// operations that are NOT part of the PUT object hot path.
@@ -2709,7 +2693,6 @@ mod tests {
        record_get_object_quorum_reached_latency("legacy_duplex", 0.002);
        record_get_object_metadata_response("legacy_duplex", "valid");
        record_get_object_metadata_fanout_shape("legacy_duplex", 4, 3, 1, 1);
-        record_get_object_metadata_fanout_lifecycle("legacy_duplex", 4, 3, 1);
        record_get_object_metadata_early_stop_hit("legacy_duplex", "valid_quorum");
        record_get_object_metadata_early_stop_miss("legacy_duplex", "insufficient_quorum");
        record_get_object_metadata_early_stop_saved_responses("legacy_duplex", 1);
@@ -2780,38 +2763,6 @@ mod tests {
        assert!(remote_scheduled >= remote_avoid_potential);
    }

-    #[test]
-    fn metadata_fanout_lifecycle_records_named_histograms() {
-        let _guard = METRICS_FLAG_LOCK.lock().unwrap_or_else(|e| e.into_inner());
-        let recorder = DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-
-        metrics::with_local_recorder(&recorder, || {
-            set_get_stage_metrics_enabled(true);
-            record_get_object_metadata_fanout_lifecycle("legacy_duplex", 4, 3, 1);
-            set_get_stage_metrics_enabled(false);
-        });
-
-        let metrics = snapshotter.snapshot().into_vec();
-        for (name, expected) in [
-            ("rustfs_io_get_object_metadata_fanout_scheduled", 4.0),
-            ("rustfs_io_get_object_metadata_fanout_completed", 3.0),
-            ("rustfs_io_get_object_metadata_fanout_cancelled", 1.0),
-        ] {
-            let value = metrics.iter().find_map(|(composite, _, _, value)| {
-                let has_path = composite
-                    .key()
-                    .labels()
-                    .any(|label| label.key() == "path" && label.value() == "legacy_duplex");
-                (composite.kind() == MetricKind::Histogram && composite.key().name() == name && has_path).then_some(value)
-            });
-            assert!(
-                matches!(value, Some(DebugValue::Histogram(values)) if values.len() == 1 && values[0].0 == expected),
-                "{name} must record the exact fanout lifecycle sample"
-            );
-        }
-    }
-
    #[test]
    fn test_record_get_object_fill_metrics() {
        record_get_object_fill_queued("codec_streaming", "single_inflight", 1);
@@ -2876,56 +2827,6 @@ mod tests {
        assert!(!put_stage_metrics_enabled());
    }

-    #[test]
-    fn put_stage_gate_does_not_disable_basic_put_metrics() {
-        let _guard = METRICS_FLAG_LOCK.lock().unwrap_or_else(|e| e.into_inner());
-        let recorder = DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-
-        metrics::with_local_recorder(&recorder, || {
-            set_metrics_enabled(true);
-            set_put_stage_metrics_enabled(false);
-            record_put_object_request_start(1);
-            record_put_object_request_result("ok", 0.001);
-            record_put_object(1.0, 1024, false);
-            record_put_object_stage_duration("disabled_stage", 0.5);
-
-            set_put_stage_metrics_enabled(true);
-            record_put_object_stage_duration("enabled_stage", 0.5);
-
-            set_put_stage_metrics_enabled(false);
-            set_metrics_enabled(false);
-        });
-
-        let metrics = snapshotter.snapshot().into_vec();
-        assert!(metrics.iter().any(|(composite, _, _, _)| {
-            composite.kind() == MetricKind::Counter && composite.key().name() == "rustfs_s3_put_object_total"
-        }));
-        assert!(metrics.iter().any(|(composite, _, _, _)| {
-            composite.kind() == MetricKind::Counter && composite.key().name() == "rustfs_io_put_object_requests_total"
-        }));
-
-        let stages = metrics
-            .iter()
-            .filter(|(composite, _, _, _)| {
-                composite.kind() == MetricKind::Histogram && composite.key().name() == "rustfs_s3_put_object_stage_duration_ms"
-            })
-            .flat_map(|(composite, _, _, _)| composite.key().labels().map(|label| label.value().to_string()))
-            .collect::<Vec<_>>();
-        assert_eq!(stages, ["enabled_stage"]);
-    }
-
-    #[test]
-    fn test_put_stage_timer_follows_metrics_switch() {
-        let _guard = METRICS_FLAG_LOCK.lock().unwrap_or_else(|e| e.into_inner());
-        set_put_stage_metrics_enabled(false);
-        assert!(put_stage_timer().is_none());
-
-        set_put_stage_metrics_enabled(true);
-        assert!(put_stage_timer().is_some());
-        set_put_stage_metrics_enabled(false);
-    }
-
    #[test]
    fn test_record_get_object_path_and_stage() {
        let _guard = METRICS_FLAG_LOCK.lock().unwrap_or_else(|e| e.into_inner());
@@ -163,46 +163,6 @@ impl LockMetricsSummary {
 #[cfg(test)]
 mod tests {
    use super::*;
-
-    /// Replaces the per-helper smoke tests that called the record_* helpers
-    /// and asserted nothing: the calls (same literals) now run against a local
-    /// DebuggingRecorder and every metric name the helpers own must actually
-    /// be emitted (rustfs/backlog#1836 PR3).
-    #[test]
-    fn record_helpers_emit_their_metrics() {
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-        metrics::with_local_recorder(&recorder, || {
-            record_lock_optimization_enabled(true);
-            record_lock_optimization_enabled(false);
-            record_spin_attempt(true);
-            record_spin_attempt(false);
-            record_spin_count_change(100);
-            record_spin_count_change(200);
-            record_lock_hold_time(Duration::from_millis(10));
-            record_lock_hold_time(Duration::from_millis(100));
-            record_early_release();
-            record_contention_event();
-        });
-
-        let emitted: std::collections::HashSet<String> = snapshotter
-            .snapshot()
-            .into_vec()
-            .into_iter()
-            .map(|(composite, _, _, _)| composite.key().name().to_string())
-            .collect();
-        for expected in [
-            "rustfs_lock_optimization_enabled",
-            "rustfs_lock_spin_successes",
-            "rustfs_lock_spin_failures",
-            "rustfs_lock_spin_count",
-            "rustfs_lock_hold_time_secs",
-            "rustfs_lock_early_releases",
-            "rustfs_lock_contentions",
-        ] {
-            assert!(emitted.contains(expected), "{expected} must be emitted by its record helper");
-        }
-    }
    use metrics::{Counter, CounterFn, Gauge, GaugeFn, Histogram, HistogramFn, Key, KeyName, Metadata, SharedString, Unit};
    use std::sync::{Arc, Mutex};

@@ -295,6 +255,40 @@ mod tests {
        fn record(&self, _value: f64) {}
    }

+    #[test]
+    fn test_record_lock_optimization_enabled() {
+        record_lock_optimization_enabled(true);
+        record_lock_optimization_enabled(false);
+    }
+
+    #[test]
+    fn test_record_spin_attempt() {
+        record_spin_attempt(true);
+        record_spin_attempt(false);
+    }
+
+    #[test]
+    fn test_record_spin_count_change() {
+        record_spin_count_change(100);
+        record_spin_count_change(200);
+    }
+
+    #[test]
+    fn test_record_lock_hold_time() {
+        record_lock_hold_time(Duration::from_millis(10));
+        record_lock_hold_time(Duration::from_millis(100));
+    }
+
+    #[test]
+    fn test_record_early_release() {
+        record_early_release();
+    }
+
+    #[test]
+    fn test_record_contention_event() {
+        record_contention_event();
+    }
+
    #[test]
    fn test_record_object_lock_diag_enabled() {
        let recorder = SeenMetricsRecorder::default();
@@ -114,46 +114,39 @@ impl TimeoutMetricsSummary {
 mod tests {
    use super::*;

-    /// Replaces the per-helper smoke tests that called the record_* helpers
-    /// and asserted nothing: the calls (same literals) now run against a local
-    /// DebuggingRecorder and every metric name the helpers own must actually
-    /// be emitted (rustfs/backlog#1836 PR3).
    #[test]
-    fn record_helpers_emit_their_metrics() {
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let snapshotter = recorder.snapshotter();
-        metrics::with_local_recorder(&recorder, || {
-            record_timeout_event("get_object");
-            record_timeout_event("put_object");
-            record_operation_duration("get_object", Duration::from_millis(100));
-            record_operation_duration("put_object", Duration::from_millis(500));
-            record_dynamic_timeout(1024 * 1024, Duration::from_secs(10));
-            record_dynamic_timeout(100 * 1024 * 1024, Duration::from_secs(30));
-            record_operation_progress("get_object", 50.0);
-            record_operation_progress("get_object", 100.0);
-            record_stalled_operation("get_object");
-            record_operation_completion("get_object", true);
-            record_operation_completion("get_object", false);
-        });
+    fn test_record_timeout_event() {
+        record_timeout_event("get_object");
+        record_timeout_event("put_object");
+    }

-        let emitted: std::collections::HashSet<String> = snapshotter
-            .snapshot()
-            .into_vec()
-            .into_iter()
-            .map(|(composite, _, _, _)| composite.key().name().to_string())
-            .collect();
-        for expected in [
-            "rustfs_io_timeout_events_total",
-            "rustfs_io_operation_duration_seconds",
-            "rustfs_timeout_dynamic_size",
-            "rustfs_timeout_dynamic_secs",
-            "rustfs_timeout_dynamic_size_histogram",
-            "rustfs_operation_progress",
-            "rustfs_operation_stalled",
-            "rustfs_operation_completions",
-        ] {
-            assert!(emitted.contains(expected), "{expected} must be emitted by its record helper");
-        }
+    #[test]
+    fn test_record_operation_duration() {
+        record_operation_duration("get_object", Duration::from_millis(100));
+        record_operation_duration("put_object", Duration::from_millis(500));
+    }
+
+    #[test]
+    fn test_record_dynamic_timeout() {
+        record_dynamic_timeout(1024 * 1024, Duration::from_secs(10));
+        record_dynamic_timeout(100 * 1024 * 1024, Duration::from_secs(30));
+    }
+
+    #[test]
+    fn test_record_operation_progress() {
+        record_operation_progress("get_object", 50.0);
+        record_operation_progress("get_object", 100.0);
+    }
+
+    #[test]
+    fn test_record_stalled_operation() {
+        record_stalled_operation("get_object");
+    }
+
+    #[test]
+    fn test_record_operation_completion() {
+        record_operation_completion("get_object", true);
+        record_operation_completion("get_object", false);
    }

    #[test]
@@ -35,10 +35,6 @@ tokio = { workspace = true, features = ["fs", "io-util", "macros", "rt-multi-thr
 uuid = { workspace = true, features = ["serde", "v4", "fast-rng", "macro-diagnostics"] }
 jiff = { workspace = true, features = ["serde"] }
 serde = { workspace = true, features = ["derive"] }
-# Observes fields a persisted-format deserialization ignored, per the
-# repository rule that formats too compatibility-bound for
-# deny_unknown_fields must at least warn (AGENTS.md).
-serde_ignored = { workspace = true }
 serde_json = { workspace = true, features = ["raw_value"] }
 tracing = { workspace = true }
 thiserror = { workspace = true }
@@ -657,7 +657,6 @@ impl KmsBackend for AwsKmsBackend {
                created_by: None,
                rotation_due: false,
                rotation_due_reason: None,
-                wrap_budget_reserved: None,
            });
        }

@@ -57,17 +57,6 @@ impl ScriptedResponse {
        }
    }

-    /// The 404 Vault answers a LIST of an empty path with: something routed the
-    /// request and found nothing under it, so the `errors` array comes back
-    /// empty. [`ScriptedResponse::error`] cannot stand in — it always fills
-    /// `errors`, which is what marks a 404 as an unrouted path instead.
-    pub(crate) fn empty_list_404() -> Self {
-        Self::Http {
-            status: 404,
-            body: serde_json::json!({ "errors": [] }).to_string(),
-        }
-    }
-
    /// Close the connection after consuming a request without sending an HTTP response.
    pub(crate) fn close() -> Self {
        Self::Close
@@ -271,7 +271,6 @@ impl StaticKmsBackend {
            created_by: None,
            rotation_due: false,
            rotation_due_reason: None,
-            wrap_budget_reserved: None,
        })
    }

@@ -27,7 +27,6 @@ use crate::backends::{
 use crate::config::{KmsConfig, VaultTransitConfig};
 use crate::encryption::{DataKeyEnvelope, generate_key_material};
 use crate::error::{KmsError, Result};
-use crate::persisted_observability::{BoundedUnknownFieldName, UnknownFieldSummary};
 use crate::policy::{self, AttemptError, OpClass, RetryPolicy};
 use crate::types::*;
 use async_trait::async_trait;
@@ -101,23 +100,6 @@ fn is_cas_conflict(error: &ClientError) -> bool {
    )
 }

-/// Whether a transit LIST failed with the 404 Vault uses for "mounted, but no
-/// keys yet".
-///
-/// Vault answers a LIST on a mounted transit engine that holds no keys with a
-/// 404 whose `errors` array is empty — the mount routed and answered the
-/// request, so the engine is reachable. A 404 for a path with no mount behind
-/// it instead carries a "no handler for route" message, so the empty `errors`
-/// array is what separates "engine reachable but empty" from "engine missing".
-///
-/// An empty non-transit engine (e.g. KV v1) at the configured path answers
-/// with byte-identical 404s, so this probe cannot detect that misconfiguration
-/// — no LIST-based probe can. The data path still fails hard on the first real
-/// transit operation against such a mount.
-fn is_empty_transit_list(error: &ClientError) -> bool {
-    matches!(error, ClientError::APIError { code: 404, errors } if errors.is_empty())
-}
-
 #[derive(Debug, Clone)]
 struct TransitKeyMetadata {
    key_usage: KeyUsage,
@@ -132,12 +114,7 @@ struct TransitKeyMetadata {
 }

 /// Serializable version of TransitKeyMetadata for KV v2 persistence.
-///
-/// `Deserialize` is hand-written so fields the current build does not know
-/// are counted and warned about instead of vanishing silently — this record
-/// is compatibility-bound in both directions (older and newer builds read
-/// each other's writes), so `deny_unknown_fields` is not an option.
-#[derive(Debug, Clone, Serialize)]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 struct TransitKeyMetadataPersisted {
    key_usage: KeyUsage,
    description: Option<String>,
@@ -150,168 +127,6 @@ struct TransitKeyMetadataPersisted {
    current_version: u32,
 }

-impl UnknownFieldSummary {
-    fn record_for_transit_key_metadata(&self) {
-        let Some((field, field_name_truncated, field_count)) = self.record("vault-transit-key-metadata") else {
-            return;
-        };
-
-        static RECORDS_WITH_UNKNOWN_FIELDS: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
-        let observed_records = RECORDS_WITH_UNKNOWN_FIELDS
-            .fetch_add(1, std::sync::atomic::Ordering::Relaxed)
-            .saturating_add(1);
-        if observed_records.is_power_of_two() {
-            tracing::warn!(
-                field = ?field,
-                field_name_truncated,
-                field_count,
-                observed_records,
-                "Vault Transit key metadata record contains unknown fields"
-            );
-        }
-    }
-}
-
-impl<'de> Deserialize<'de> for TransitKeyMetadataPersisted {
-    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
-    where
-        D: serde::Deserializer<'de>,
-    {
-        use serde::de::{self, IgnoredAny, MapAccess, Visitor};
-        use std::fmt;
-
-        enum Field {
-            KeyUsage,
-            Description,
-            Tags,
-            KeyState,
-            CreatedAt,
-            DeletionDate,
-            Origin,
-            CreatedBy,
-            CurrentVersion,
-            Unknown(BoundedUnknownFieldName),
-        }
-
-        impl<'de> Deserialize<'de> for Field {
-            fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
-            where
-                D: serde::Deserializer<'de>,
-            {
-                struct FieldVisitor;
-
-                impl Visitor<'_> for FieldVisitor {
-                    type Value = Field;
-
-                    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
-                        formatter.write_str("a Vault Transit key metadata field name")
-                    }
-
-                    fn visit_str<E>(self, value: &str) -> std::result::Result<Self::Value, E>
-                    where
-                        E: de::Error,
-                    {
-                        Ok(match value {
-                            "key_usage" => Field::KeyUsage,
-                            "description" => Field::Description,
-                            "tags" => Field::Tags,
-                            "key_state" => Field::KeyState,
-                            "created_at" => Field::CreatedAt,
-                            "deletion_date" => Field::DeletionDate,
-                            "origin" => Field::Origin,
-                            "created_by" => Field::CreatedBy,
-                            "current_version" => Field::CurrentVersion,
-                            _ => Field::Unknown(BoundedUnknownFieldName::new(value)),
-                        })
-                    }
-                }
-
-                deserializer.deserialize_identifier(FieldVisitor)
-            }
-        }
-
-        struct TransitKeyMetadataPersistedVisitor;
-
-        impl<'de> Visitor<'de> for TransitKeyMetadataPersistedVisitor {
-            type Value = TransitKeyMetadataPersisted;
-
-            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
-                formatter.write_str("a Vault Transit key metadata record")
-            }
-
-            fn visit_map<A>(self, mut map: A) -> std::result::Result<Self::Value, A::Error>
-            where
-                A: MapAccess<'de>,
-            {
-                macro_rules! read_field {
-                    ($slot:ident, $name:literal) => {{
-                        if $slot.is_some() {
-                            return Err(de::Error::duplicate_field($name));
-                        }
-                        $slot = Some(map.next_value()?);
-                    }};
-                }
-
-                let mut key_usage = None;
-                let mut description = None;
-                let mut tags = None;
-                let mut key_state = None;
-                let mut created_at = None;
-                let mut deletion_date = None;
-                let mut origin = None;
-                let mut created_by = None;
-                let mut current_version = None;
-                let mut unknown_fields = UnknownFieldSummary::default();
-
-                while let Some(field) = map.next_key()? {
-                    match field {
-                        Field::KeyUsage => read_field!(key_usage, "key_usage"),
-                        Field::Description => read_field!(description, "description"),
-                        Field::Tags => read_field!(tags, "tags"),
-                        Field::KeyState => read_field!(key_state, "key_state"),
-                        Field::CreatedAt => read_field!(created_at, "created_at"),
-                        Field::DeletionDate => read_field!(deletion_date, "deletion_date"),
-                        Field::Origin => read_field!(origin, "origin"),
-                        Field::CreatedBy => read_field!(created_by, "created_by"),
-                        Field::CurrentVersion => read_field!(current_version, "current_version"),
-                        Field::Unknown(field) => {
-                            let _: IgnoredAny = map.next_value()?;
-                            unknown_fields.observe(field);
-                        }
-                    }
-                }
-
-                let metadata = TransitKeyMetadataPersisted {
-                    key_usage: key_usage.ok_or_else(|| de::Error::missing_field("key_usage"))?,
-                    description: description.unwrap_or(None),
-                    tags: tags.ok_or_else(|| de::Error::missing_field("tags"))?,
-                    key_state: key_state.ok_or_else(|| de::Error::missing_field("key_state"))?,
-                    created_at: created_at.ok_or_else(|| de::Error::missing_field("created_at"))?,
-                    deletion_date: deletion_date.unwrap_or(None),
-                    origin: origin.ok_or_else(|| de::Error::missing_field("origin"))?,
-                    created_by: created_by.unwrap_or(None),
-                    current_version: current_version.ok_or_else(|| de::Error::missing_field("current_version"))?,
-                };
-                unknown_fields.record_for_transit_key_metadata();
-                Ok(metadata)
-            }
-        }
-
-        const FIELDS: &[&str] = &[
-            "key_usage",
-            "description",
-            "tags",
-            "key_state",
-            "created_at",
-            "deletion_date",
-            "origin",
-            "created_by",
-            "current_version",
-        ];
-        deserializer.deserialize_struct("TransitKeyMetadataPersisted", FIELDS, TransitKeyMetadataPersistedVisitor)
-    }
-}
-
 impl TransitKeyMetadata {
    fn from_create_request(request: &CreateKeyRequest) -> Self {
        Self {
@@ -891,7 +706,6 @@ impl VaultTransitKmsClient {
            created_by: metadata.created_by,
            rotation_due: false,
            rotation_due_reason: None,
-            wrap_budget_reserved: None,
        })
    }

@@ -1260,17 +1074,12 @@ impl VaultTransitKmsClient {
        let mut all_keys = self
            .run("vault_transit_list_keys", OpClass::ReadIdempotent, move || async move {
                let vault = self.vault().map_err(AttemptError::fatal)?;
-                match key::list(&vault.client, &self.config.mount_path).await {
-                    Ok(response) => Ok(response.keys),
-                    // An empty transit engine answers LIST with a bare 404;
-                    // that is an empty listing, not a backend failure.
-                    Err(error) if is_empty_transit_list(&error) => Ok(Vec::new()),
-                    Err(e) => Err(AttemptError::from_vaultrs(e, |e| {
-                        KmsError::backend_error(format!("Failed to list Vault Transit keys: {e}"))
-                    })),
-                }
+                key::list(&vault.client, &self.config.mount_path).await.map_err(|e| {
+                    AttemptError::from_vaultrs(e, |e| KmsError::backend_error(format!("Failed to list Vault Transit keys: {e}")))
+                })
            })
-            .await?;
+            .await?
+            .keys;
        // Vault's own LIST ordering is not part of its contract, so the sort is
        // what makes the marker a stable cursor across calls.
        all_keys.sort_unstable();
@@ -1443,17 +1252,12 @@ impl VaultTransitKmsClient {
    pub(crate) async fn health_check(&self) -> Result<()> {
        self.run("vault_transit_health_check", OpClass::ReadIdempotent, move || async move {
            let vault = self.vault().map_err(AttemptError::fatal)?;
-            match key::list(&vault.client, &self.config.mount_path).await {
-                Ok(_) => Ok(()),
-                // A brand-new transit mount holds no keys until something
-                // creates one, and this check gates startup before the service
-                // creates its own probe key — treating "empty" as unhealthy
-                // would keep a first-ever deployment from ever starting.
-                Err(error) if is_empty_transit_list(&error) => Ok(()),
-                Err(e) => Err(AttemptError::from_vaultrs(e, |e| {
-                    KmsError::backend_error(format!("Vault Transit health check failed: {e}"))
-                })),
-            }
+            key::list(&vault.client, &self.config.mount_path)
+                .await
+                .map(|_| ())
+                .map_err(|e| {
+                    AttemptError::from_vaultrs(e, |e| KmsError::backend_error(format!("Vault Transit health check failed: {e}")))
+                })
        })
        .await
    }
@@ -2112,107 +1916,6 @@ mod tests {
        );
    }

-    /// Regression test for the first-boot chicken-and-egg on a fresh transit
-    /// mount (rustfs/backlog#1774).
-    ///
-    /// Vault answers a LIST on a mounted-but-empty transit engine with a 404
-    /// carrying an empty `errors` array. The health check gates startup before
-    /// the service creates its probe key, so this 404 must count as healthy —
-    /// failing it means a first-ever deployment on a fresh mount can never
-    /// start until an operator creates some transit key out-of-band.
-    #[tokio::test]
-    async fn health_check_passes_on_an_empty_transit_engine() {
-        let (vault, client) = scripted_client(vec![ScriptedResponse::Http {
-            status: 404,
-            body: serde_json::json!({ "errors": [] }).to_string(),
-        }])
-        .await;
-
-        client
-            .health_check()
-            .await
-            .expect("an empty transit engine is reachable and must pass the health check");
-
-        let requests = vault.requests();
-        assert_eq!(
-            requests,
-            vec!["LIST /v1/transit/keys".to_string()],
-            "the empty-list 404 must be accepted on the first attempt, not retried"
-        );
-    }
-
-    /// A 404 whose body says "no handler for route" means no transit engine is
-    /// mounted at the configured path at all; that must keep failing the
-    /// health check instead of riding the empty-engine allowance.
-    #[tokio::test]
-    async fn health_check_fails_when_the_transit_mount_is_missing() {
-        let (_vault, client) = scripted_client(vec![ScriptedResponse::error(
-            404,
-            "no handler for route \"transit/keys\". route entry not found.",
-        )])
-        .await;
-
-        let error = client
-            .health_check()
-            .await
-            .expect_err("a missing transit mount must fail the health check");
-        assert!(matches!(error, KmsError::BackendError { .. }), "got {error:?}");
-    }
-
-    /// The empty-engine allowance is scoped to 404 alone: any other status
-    /// whose body happens to carry an empty `errors` array (an intermediary
-    /// answering for Vault, for instance) must keep failing the health check.
-    #[tokio::test]
-    async fn health_check_fails_on_a_non_404_error_with_an_empty_errors_body() {
-        let (_vault, client) = scripted_client(vec![ScriptedResponse::Http {
-            status: 403,
-            body: serde_json::json!({ "errors": [] }).to_string(),
-        }])
-        .await;
-
-        let error = client
-            .health_check()
-            .await
-            .expect_err("only a 404 may ride the empty-engine allowance");
-        assert!(matches!(error, KmsError::BackendError { .. }), "got {error:?}");
-    }
-
-    /// The listing's own copy of the discriminator must not widen into "every
-    /// LIST failure is an empty listing" — a missing mount still fails loudly.
-    #[tokio::test]
-    async fn list_fails_when_the_transit_mount_is_missing() {
-        let (_vault, client) = scripted_client(vec![ScriptedResponse::error(
-            404,
-            "no handler for route \"transit/keys\". route entry not found.",
-        )])
-        .await;
-
-        let error = client
-            .list_keys(&ListKeysRequest::default(), None)
-            .await
-            .expect_err("a missing transit mount must fail the listing, not empty it");
-        assert!(matches!(error, KmsError::BackendError { .. }), "got {error:?}");
-    }
-
-    /// The same empty-engine 404 on the listing path is an empty result set,
-    /// not a backend failure.
-    #[tokio::test]
-    async fn list_keys_returns_an_empty_page_on_an_empty_transit_engine() {
-        let (_vault, client) = scripted_client(vec![ScriptedResponse::Http {
-            status: 404,
-            body: serde_json::json!({ "errors": [] }).to_string(),
-        }])
-        .await;
-
-        let response = client
-            .list_keys(&ListKeysRequest::default(), None)
-            .await
-            .expect("an empty transit engine must list as empty, not fail");
-        assert!(response.keys.is_empty(), "got {:?}", response.keys);
-        assert!(!response.truncated, "an empty listing has nothing left to page through");
-        assert_eq!(response.next_marker, None);
-    }
-
    fn test_vault_transit_config() -> VaultTransitConfig {
        VaultTransitConfig {
            address: "http://127.0.0.1:8200".to_string(),
@@ -2430,41 +2133,6 @@ mod tests {
        assert!(metadata.deletion_date.is_none());
    }

-    #[test]
-    fn transit_key_metadata_unknown_fields_remain_readable_and_are_observed() {
-        // A record written by a newer build carries fields this build does not
-        // know. It must stay readable — and the drop must be visible, not
-        // silent (rustfs/backlog#1641). Only the field name may be logged.
-        let persisted: TransitKeyMetadataPersisted = TransitKeyMetadata::synthesized().into();
-        let mut value = serde_json::to_value(&persisted).expect("serialize metadata record");
-        let object = value.as_object_mut().expect("metadata record serializes to an object");
-        object.insert("field_from_the_future".to_string(), serde_json::json!("field value must not be logged"));
-
-        let logs = crate::test_support::CapturedLogs::default();
-        let subscriber = tracing_subscriber::fmt()
-            .with_ansi(false)
-            .with_max_level(tracing::Level::WARN)
-            .with_writer(logs.clone())
-            .finish();
-        let dispatch = tracing::Dispatch::new(subscriber);
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let parsed: TransitKeyMetadataPersisted = metrics::with_local_recorder(&recorder, || {
-            tracing::dispatcher::with_default(&dispatch, || {
-                serde_json::from_value(value).expect("unknown fields must remain readable")
-            })
-        });
-        assert_eq!(parsed.key_state, KeyState::Enabled);
-        assert_eq!(crate::test_support::unknown_field_metric(&recorder, "vault-transit-key-metadata"), 1);
-
-        let output = logs.output();
-        assert!(
-            output.contains("Vault Transit key metadata record contains unknown fields"),
-            "got: {output}"
-        );
-        assert!(output.contains("field_from_the_future"));
-        assert!(!output.contains("field value must not be logged"));
-    }
-
    /// KV2 write acknowledgement (`SecretVersionMetadata`) for `kv2::set`.
    fn kv2_write_ack() -> serde_json::Value {
        serde_json::json!({
@@ -868,14 +868,6 @@ impl KmsConfig {
                // `mount_path` is deprecated and unused by this backend, so an empty value
                // is deliberately not an error.

-                // `kv_mount` is: it is the mount every read, write and listing is
-                // routed through, and an empty one produces a path Vault has no
-                // handler for. Rejecting it here names the setting; letting it
-                // through spends a round-trip to report an unroutable path.
-                if config.kv_mount.is_empty() {
-                    return Err(KmsError::configuration_error("Vault KV2 mount cannot be empty"));
-                }
-
                // Validate TLS configuration if using HTTPS
                if config.address.starts_with("https://")
                    && let Some(ref tls) = config.tls
@@ -1137,53 +1129,6 @@ pub fn allow_immediate_deletion_from_env() -> bool {
    get_env_bool(ENV_KMS_ALLOW_IMMEDIATE_DELETION, false)
 }

-impl crate::persisted_observability::UnknownFieldSummary {
-    fn record_for_kms_config(&self) {
-        let Some((field, field_name_truncated, field_count)) = self.record("kms-config") else {
-            return;
-        };
-
-        static RECORDS_WITH_UNKNOWN_FIELDS: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
-        let observed_records = RECORDS_WITH_UNKNOWN_FIELDS
-            .fetch_add(1, std::sync::atomic::Ordering::Relaxed)
-            .saturating_add(1);
-        if observed_records.is_power_of_two() {
-            tracing::warn!(
-                field = ?field,
-                field_name_truncated,
-                field_count,
-                observed_records,
-                "persisted KMS configuration contains unknown fields"
-            );
-        }
-    }
-}
-
-/// Deserialize a persisted KMS configuration, observing ignored fields.
-///
-/// The persisted configuration deliberately tolerates unknown fields — a
-/// rolling upgrade writes fields the previous build does not know, and
-/// rejecting them would turn every upgrade into a hard stop (see the
-/// regression test pinning that tolerance). Tolerated must not mean
-/// invisible: this loader wraps the deserializer with `serde_ignored`, so
-/// every field the configuration silently dropped is counted and sampled
-/// into a warning, per the repository rule that formats too
-/// compatibility-bound for `deny_unknown_fields` must at least log unknown
-/// fields. Only field paths are recorded, never values — a mistyped field
-/// name can sit next to a secret.
-pub fn kms_config_from_persisted_json(data: &[u8]) -> serde_json::Result<KmsConfig> {
-    use crate::persisted_observability::{BoundedUnknownFieldName, UnknownFieldSummary};
-
-    let mut deserializer = serde_json::Deserializer::from_slice(data);
-    let mut unknown_fields = UnknownFieldSummary::default();
-    let config: KmsConfig = serde_ignored::deserialize(&mut deserializer, |path| {
-        unknown_fields.observe(BoundedUnknownFieldName::new(&path.to_string()));
-    })?;
-    deserializer.end()?;
-    unknown_fields.record_for_kms_config();
-    Ok(config)
-}
-
 fn vault_tls_config(skip_tls_verify: bool) -> Option<TlsConfig> {
    skip_tls_verify.then_some(TlsConfig {
        ca_cert_path: None,
@@ -1975,34 +1920,6 @@ mod tests {
            .expect("well-formed token file auth must validate");
    }

-    /// Every KV2 read, write and listing is routed through `kv_mount`, so an
-    /// empty one names a path no Vault engine answers. The Transit backend
-    /// already rejects its own empty mounts; this closes the same gap on the
-    /// setting whose absence otherwise surfaces as an unroutable-path failure at
-    /// the first Vault call.
-    #[test]
-    fn test_validate_rejects_an_empty_kv2_mount() {
-        let kv2_config = |kv_mount: &str| KmsConfig {
-            backend: KmsBackend::VaultKv2,
-            backend_config: BackendConfig::VaultKv2(Box::new(VaultConfig {
-                address: "https://vault.example.com:8200".to_string(),
-                auth_method: VaultAuthMethod::Token {
-                    token: "a-real-token".to_string(),
-                },
-                kv_mount: kv_mount.to_string(),
-                ..Default::default()
-            })),
-            ..Default::default()
-        };
-
-        let error = kv2_config("")
-            .validate()
-            .expect_err("an empty KV2 mount must be rejected as a configuration error");
-        assert!(error.to_string().contains("mount"), "got {error}");
-
-        kv2_config("secret").validate().expect("a named KV2 mount must validate");
-    }
-
    #[test]
    fn test_approle_config_deserializes_legacy_shape_with_defaults() {
        // Persisted configurations from before the AppRole implementation only
@@ -2062,58 +1979,6 @@ mod tests {
        });
    }

-    #[test]
-    fn persisted_config_unknown_fields_remain_readable_and_are_observed() {
-        // Unknown fields in a persisted config are deliberately tolerated (a
-        // rolling upgrade writes fields the previous build does not know), but
-        // tolerated must not mean invisible (rustfs/backlog#1641): the
-        // observing loader counts and warns, naming only the field path —
-        // never the value, which can sit next to a secret. Coverage includes a
-        // field nested inside the backend variant, which the externally tagged
-        // enum exposes to the observer.
-        let mut value = serde_json::to_value(KmsConfig::default()).expect("serialize config");
-        value.as_object_mut().expect("config serializes to an object").insert(
-            "top_level_field_from_the_future".to_string(),
-            serde_json::json!("top-level value must not be logged"),
-        );
-        value
-            .pointer_mut("/backend_config/Local")
-            .expect("default config has a Local backend section")
-            .as_object_mut()
-            .expect("Local backend section is an object")
-            .insert(
-                "nested_field_from_the_future".to_string(),
-                serde_json::json!("nested value must not be logged"),
-            );
-        let data = serde_json::to_vec(&value).expect("encode config");
-
-        let logs = crate::test_support::CapturedLogs::default();
-        let subscriber = tracing_subscriber::fmt()
-            .with_ansi(false)
-            .with_max_level(tracing::Level::WARN)
-            .with_writer(logs.clone())
-            .finish();
-        let dispatch = tracing::Dispatch::new(subscriber);
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        let config = metrics::with_local_recorder(&recorder, || {
-            tracing::dispatcher::with_default(&dispatch, || {
-                kms_config_from_persisted_json(&data).expect("unknown fields must remain readable")
-            })
-        });
-        assert!(matches!(config.backend_config, BackendConfig::Local(_)));
-        assert_eq!(crate::test_support::unknown_field_metric(&recorder, "kms-config"), 2);
-
-        let output = logs.output();
-        assert!(output.contains("persisted KMS configuration contains unknown fields"), "got: {output}");
-        assert!(!output.contains("must not be logged"));
-
-        // A clean config observes nothing and logs nothing.
-        let clean = serde_json::to_vec(&KmsConfig::default()).expect("encode clean config");
-        let recorder = metrics_util::debugging::DebuggingRecorder::new();
-        metrics::with_local_recorder(&recorder, || kms_config_from_persisted_json(&clean).expect("clean config must parse"));
-        assert_eq!(crate::test_support::unknown_field_metric(&recorder, "kms-config"), 0);
-    }
-
    #[test]
    fn test_validate_rejects_incomplete_approle() {
        let mut config = KmsConfig::vault_approle(
@@ -62,12 +62,6 @@ const METRIC_TOMBSTONE_KEYS: &str = "rustfs_kms_deletion_tombstone_keys";
 /// Gauge: seconds since the least recently rotated usable key was rotated
 /// (its creation time when it was never rotated); `0` when there are none.
 const METRIC_OLDEST_ROTATION_AGE_SECONDS: &str = "rustfs_kms_oldest_key_rotation_age_seconds";
-/// Gauge: the largest persisted wrap-operation reservation across usable keys,
-/// as of the end of the last sweep that saw the whole key set. Published only
-/// when the backend counts wraps (the Vault KV2 backend today); an aggregate
-/// that by design overestimates actual wraps. The value to alert on against
-/// the AES-256-GCM bound of 2^32 wraps per key material.
-const METRIC_MAX_KEY_WRAP_OPERATIONS: &str = "rustfs_kms_max_key_wrap_operations";
 /// Counter: keys the sweep acted on, by `outcome` (`removed`, `blocked`,
 /// `skipped`, `failed`, `unreadable`).
 const METRIC_SWEEP_KEYS_TOTAL: &str = "rustfs_kms_deletion_sweep_keys_total";
@@ -88,10 +82,6 @@ fn describe_metrics() {
            METRIC_OLDEST_ROTATION_AGE_SECONDS,
            "Seconds since the least recently rotated usable KMS key was last rotated, counting from creation for keys that were never rotated"
        );
-        metrics::describe_gauge!(
-            METRIC_MAX_KEY_WRAP_OPERATIONS,
-            "Largest reserved wrap-operation count across usable KMS keys; overestimates actual wraps and is only reported by backends that count them"
-        );
        metrics::describe_counter!(METRIC_SWEEP_KEYS_TOTAL, "Total keys acted on by the KMS deletion sweep, by outcome");
    });
 }
@@ -109,11 +99,6 @@ struct KeyCensus {
    /// way out are excluded: they will never be rotated again, and would
    /// otherwise pin the gauge high until the sweep finishes removing them.
    oldest_rotation_age_seconds: f64,
-    /// Largest reserved wrap count across usable keys, `None` when no key
-    /// reported one — either the backend does not count wraps, or no usable
-    /// key was seen. Excluding departing keys mirrors the rotation age: their
-    /// material will never wrap again, so its consumed nonce budget is moot.
-    max_wrap_operations: Option<u64>,
 }

 impl KeyCensus {
@@ -122,9 +107,6 @@ impl KeyCensus {
            KeyStatus::PendingDeletion => self.pending_deletion += 1,
            KeyStatus::Deleted => self.tombstones += 1,
            KeyStatus::Active | KeyStatus::Disabled => {
-                if let Some(reserved) = key.wrap_budget_reserved {
-                    self.max_wrap_operations = Some(self.max_wrap_operations.unwrap_or(0).max(reserved));
-                }
                // A missing rotation time means either "never rotated" or "the
                // build that rotated it did not record when". Both fall back to
                // creation, and the two are not worth separate series: for the
@@ -172,11 +154,6 @@ fn record_sweep(report: &SweepReport, census: Option<KeyCensus>) {
    metrics::gauge!(METRIC_PENDING_DELETION_KEYS).set(census.pending_deletion as f64);
    metrics::gauge!(METRIC_TOMBSTONE_KEYS).set(census.tombstones as f64);
    metrics::gauge!(METRIC_OLDEST_ROTATION_AGE_SECONDS).set(census.oldest_rotation_age_seconds);
-    // Only emitted when a usable key reported a count: backends that do not
-    // count wraps must not publish a `0` that reads as "no wraps consumed".
-    if let Some(max_wrap_operations) = census.max_wrap_operations {
-        metrics::gauge!(METRIC_MAX_KEY_WRAP_OPERATIONS).set(max_wrap_operations as f64);
-    }
 }

 /// Reports configuration that still references a KMS key.
@@ -795,7 +772,6 @@ mod tests {
            created_by: None,
            rotation_due: false,
            rotation_due_reason: None,
-            wrap_budget_reserved: None,
        }
    }

@@ -827,63 +803,6 @@ mod tests {
        );
    }

-    /// The wrap census is the max over usable keys that report a counter.
-    /// Keys without one (backends that do not count wraps) leave it `None`
-    /// rather than dragging in a zero, and departing keys are excluded — their
-    /// material never wraps again, so its consumed nonce budget is moot.
-    #[test]
-    fn census_takes_the_max_wrap_reservation_of_usable_keys_only() {
-        let now = Zoned::now();
-        let mut census = KeyCensus::default();
-
-        census.observe(&key_info("uncounted", KeyStatus::Active, now.clone(), None), &now);
-        assert_eq!(census.max_wrap_operations, None, "a key without a counter must not report zero");
-
-        let mut low = key_info("low", KeyStatus::Active, now.clone(), None);
-        low.wrap_budget_reserved = Some(1_000_000);
-        let mut high = key_info("high", KeyStatus::Disabled, now.clone(), None);
-        high.wrap_budget_reserved = Some(3_000_000);
-        let mut departing = key_info("departing", KeyStatus::PendingDeletion, now.clone(), None);
-        departing.wrap_budget_reserved = Some(9_000_000);
-        census.observe(&low, &now);
-        census.observe(&high, &now);
-        census.observe(&departing, &now);
-
-        assert_eq!(census.max_wrap_operations, Some(3_000_000));
-    }
-
-    /// The wrap gauge is a single aggregate: one value, no labels at all — a
-    /// per-key label would carry key identifiers into the metric stream and
-    /// grow the series count with the key set.
-    #[test]
-    fn wrap_budget_gauge_is_aggregate_and_carries_no_key_label() {
-        let (snapshot, ()) = record_metrics(|| {
-            Box::pin(async {
-                let now = Zoned::now();
-                let mut census = KeyCensus::default();
-                let mut wrapped = key_info("wrapped-key-id", KeyStatus::Active, now.clone(), None);
-                wrapped.wrap_budget_reserved = Some(2_000_000);
-                census.observe(&wrapped, &now);
-                record_sweep(&SweepReport::default(), Some(census));
-            })
-        });
-
-        assert_eq!(gauge_value(&snapshot, METRIC_MAX_KEY_WRAP_OPERATIONS), Some(2_000_000.0));
-        for (composite, ..) in &snapshot {
-            if composite.key().name() == METRIC_MAX_KEY_WRAP_OPERATIONS {
-                assert_eq!(composite.key().labels().count(), 0, "the wrap gauge must stay label-less");
-            }
-            for label in composite.key().labels() {
-                assert!(
-                    !label.value().contains("wrapped-key-id"),
-                    "metric {} leaked a key identifier through label {}",
-                    composite.key().name(),
-                    label.key()
-                );
-            }
-        }
-    }
-
    #[test]
    fn sweep_publishes_lifecycle_gauges_without_key_labels() {
        let (snapshot, key_ids) = record_metrics(|| {
@@ -916,11 +835,6 @@ mod tests {
        );
        assert_eq!(counter_value(&snapshot, METRIC_SWEEP_KEYS_TOTAL, "skipped"), 1);
        assert_eq!(counter_value(&snapshot, METRIC_SWEEP_KEYS_TOTAL, "removed"), 0);
-        assert_eq!(
-            gauge_value(&snapshot, METRIC_MAX_KEY_WRAP_OPERATIONS),
-            None,
-            "a backend that does not count wraps must not publish a wrap gauge that reads as zero consumption"
-        );

        for (composite, ..) in &snapshot {
            for label in composite.key().labels() {
@@ -1707,7 +1707,6 @@ mod tests {
            created_by: None,
            rotation_due: false,
            rotation_due_reason: None,
-            wrap_budget_reserved: None,
        }
    }

--- a/Show More
+++ b/Show More