feat(scanner): add source-aware maintenance controls (#3461)

* feat(scanner): add source-aware maintenance controls

* fix(scanner): preserve source control between cycles

---------

Co-authored-by: Henry Guo <marshawcoco@users.noreply.github.com>

crates/common/src/metrics.rs

@@ -762,6 +762,34 @@ pub struct ScannerSourceWorkSnapshot {
     pub missed: u64,
 }
 
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ScannerMaintenanceSourceSnapshot {
+    pub source: String,
+    pub state: String,
+    pub reason: String,
+    pub backlog: u64,
+    pub current_checked: u64,
+    pub current_queued: u64,
+    pub current_missed: u64,
+    pub lifetime_missed: u64,
+    pub partial_cycles: u64,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ScannerMaintenanceControlSnapshot {
+    pub primary_control: String,
+    pub sources: Vec<ScannerMaintenanceSourceSnapshot>,
+}
+
+impl Default for ScannerMaintenanceControlSnapshot {
+    fn default() -> Self {
+        Self {
+            primary_control: SCANNER_MAINTENANCE_CONTROL_NONE.to_string(),
+            sources: Vec::new(),
+        }
+    }
+}
+
 #[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
 pub struct ScannerSourceCycleSnapshot {
     pub source: String,
@@ -940,6 +968,8 @@ pub struct ScannerMetricsReport {
     #[serde(default)]
     pub lifecycle_transition: ScannerLifecycleTransitionSnapshot,
     #[serde(default)]
+    pub maintenance_control: ScannerMaintenanceControlSnapshot,
+    #[serde(default)]
     pub throttle_idle_mode_enabled: bool,
     #[serde(default)]
     pub throttle_sleep_factor: f64,
@@ -1090,6 +1120,164 @@ fn scanner_pacing_pressure(metrics: &ScannerMetricsReport) -> ScannerPacingPress
     }
 }
 
+const SCANNER_MAINTENANCE_CONTROL_NONE: &str = "none";
+const SCANNER_MAINTENANCE_CONTROL_BLOCKED_SOURCE: &str = "blocked_source";
+const SCANNER_MAINTENANCE_CONTROL_DEFERRED_SOURCE: &str = "deferred_source";
+const SCANNER_MAINTENANCE_CONTROL_ACTIVE_SOURCE: &str = "active_source";
+const SCANNER_MAINTENANCE_CONTROL_PACING_PRESSURE: &str = "pacing_pressure";
+
+const SCANNER_MAINTENANCE_STATE_IDLE: &str = "idle";
+const SCANNER_MAINTENANCE_STATE_ACTIVE: &str = "active";
+const SCANNER_MAINTENANCE_STATE_DEFERRED: &str = "deferred";
+const SCANNER_MAINTENANCE_STATE_BLOCKED: &str = "blocked";
+
+const SCANNER_MAINTENANCE_REASON_IDLE: &str = "idle";
+const SCANNER_MAINTENANCE_REASON_ACTIVE_WORK: &str = "active_work";
+const SCANNER_MAINTENANCE_REASON_QUEUED_WORK: &str = "queued_work";
+const SCANNER_MAINTENANCE_REASON_PARTIAL_CYCLE: &str = "partial_cycle";
+const SCANNER_MAINTENANCE_REASON_MISSED_WORK: &str = "missed_work";
+const SCANNER_MAINTENANCE_REASON_TRANSITION_QUEUE_BACKLOG: &str = "transition_queue_backlog";
+const SCANNER_MAINTENANCE_REASON_TRANSITION_QUEUE_FULL: &str = "transition_queue_full";
+
+fn scanner_source_work_snapshot(work: &[ScannerSourceWorkSnapshot], source: ScannerWorkSource) -> ScannerSourceWorkSnapshot {
+    work.iter()
+        .find(|snapshot| snapshot.source == source.as_str())
+        .cloned()
+        .unwrap_or_else(|| ScannerSourceWorkSnapshot {
+            source: source.as_str().to_string(),
+            ..Default::default()
+        })
+}
+
+fn scanner_source_partial_cycles(metrics: &ScannerMetricsReport, source: ScannerWorkSource) -> u64 {
+    metrics
+        .partial_cycles_by_source
+        .iter()
+        .find(|snapshot| snapshot.source == source.as_str())
+        .map(|snapshot| snapshot.cycles)
+        .unwrap_or_default()
+}
+
+fn scanner_source_has_current_work(work: &ScannerSourceWorkSnapshot) -> bool {
+    work.checked > 0 || work.queued > 0 || work.executed > 0 || work.failed > 0 || work.skipped > 0 || work.missed > 0
+}
+
+fn scanner_lifecycle_transition_backlog(metrics: &ScannerMetricsReport) -> u64 {
+    metrics
+        .lifecycle_transition
+        .current_queued
+        .saturating_add(metrics.lifecycle_transition.current_active)
+}
+
+fn scanner_source_maintenance_state(
+    source: ScannerWorkSource,
+    current: &ScannerSourceWorkSnapshot,
+    metrics: &ScannerMetricsReport,
+) -> (&'static str, &'static str, u64) {
+    if current.missed > 0 {
+        return (SCANNER_MAINTENANCE_STATE_BLOCKED, SCANNER_MAINTENANCE_REASON_MISSED_WORK, current.missed);
+    }
+
+    if source == ScannerWorkSource::Lifecycle {
+        let transition_backlog = scanner_lifecycle_transition_backlog(metrics);
+        if metrics.lifecycle_transition.current_queue_capacity > 0
+            && metrics.lifecycle_transition.current_queued >= metrics.lifecycle_transition.current_queue_capacity
+        {
+            return (
+                SCANNER_MAINTENANCE_STATE_BLOCKED,
+                SCANNER_MAINTENANCE_REASON_TRANSITION_QUEUE_FULL,
+                transition_backlog,
+            );
+        }
+    }
+
+    if metrics.last_cycle_partial_source == source.as_str() && metrics.pacing_pressure.last_cycle_budget_limited {
+        return (SCANNER_MAINTENANCE_STATE_DEFERRED, SCANNER_MAINTENANCE_REASON_PARTIAL_CYCLE, 0);
+    }
+
+    if current.queued > 0 {
+        return (SCANNER_MAINTENANCE_STATE_ACTIVE, SCANNER_MAINTENANCE_REASON_QUEUED_WORK, current.queued);
+    }
+
+    if source == ScannerWorkSource::Lifecycle {
+        let transition_backlog = scanner_lifecycle_transition_backlog(metrics);
+        if transition_backlog > 0 {
+            return (
+                SCANNER_MAINTENANCE_STATE_ACTIVE,
+                SCANNER_MAINTENANCE_REASON_TRANSITION_QUEUE_BACKLOG,
+                transition_backlog,
+            );
+        }
+    }
+
+    if scanner_source_has_current_work(current) {
+        return (SCANNER_MAINTENANCE_STATE_ACTIVE, SCANNER_MAINTENANCE_REASON_ACTIVE_WORK, 0);
+    }
+
+    (SCANNER_MAINTENANCE_STATE_IDLE, SCANNER_MAINTENANCE_REASON_IDLE, 0)
+}
+
+fn scanner_maintenance_source_work(metrics: &ScannerMetricsReport) -> &[ScannerSourceWorkSnapshot] {
+    if metrics.current_cycle_source_work.is_empty() {
+        &metrics.last_cycle_source_work
+    } else {
+        &metrics.current_cycle_source_work
+    }
+}
+
+fn scanner_maintenance_control(metrics: &ScannerMetricsReport) -> ScannerMaintenanceControlSnapshot {
+    let mut has_blocked = false;
+    let mut has_deferred = false;
+    let mut has_active = false;
+    let current_source_work = scanner_maintenance_source_work(metrics);
+
+    let sources = ScannerWorkSource::all()
+        .iter()
+        .map(|source| {
+            let current = scanner_source_work_snapshot(current_source_work, *source);
+            let lifetime = scanner_source_work_snapshot(&metrics.source_work, *source);
+            let partial_cycles = scanner_source_partial_cycles(metrics, *source);
+            let (state, reason, backlog) = scanner_source_maintenance_state(*source, &current, metrics);
+
+            match state {
+                SCANNER_MAINTENANCE_STATE_BLOCKED => has_blocked = true,
+                SCANNER_MAINTENANCE_STATE_DEFERRED => has_deferred = true,
+                SCANNER_MAINTENANCE_STATE_ACTIVE => has_active = true,
+                _ => {}
+            }
+
+            ScannerMaintenanceSourceSnapshot {
+                source: source.as_str().to_string(),
+                state: state.to_string(),
+                reason: reason.to_string(),
+                backlog,
+                current_checked: current.checked,
+                current_queued: current.queued,
+                current_missed: current.missed,
+                lifetime_missed: lifetime.missed,
+                partial_cycles,
+            }
+        })
+        .collect();
+
+    let primary_control = if has_blocked {
+        SCANNER_MAINTENANCE_CONTROL_BLOCKED_SOURCE
+    } else if has_deferred {
+        SCANNER_MAINTENANCE_CONTROL_DEFERRED_SOURCE
+    } else if has_active {
+        SCANNER_MAINTENANCE_CONTROL_ACTIVE_SOURCE
+    } else if metrics.pacing_pressure.primary_pressure != SCANNER_MAINTENANCE_CONTROL_NONE {
+        SCANNER_MAINTENANCE_CONTROL_PACING_PRESSURE
+    } else {
+        SCANNER_MAINTENANCE_CONTROL_NONE
+    };
+
+    ScannerMaintenanceControlSnapshot {
+        primary_control: primary_control.to_string(),
+        sources,
+    }
+}
+
 fn duration_millis_saturated(duration: Duration) -> u64 {
     duration.as_millis().min(u64::MAX as u128) as u64
 }
@@ -2163,6 +2351,7 @@ impl Metrics {
         }
 
         m.pacing_pressure = scanner_pacing_pressure(&m);
+        m.maintenance_control = scanner_maintenance_control(&m);
 
         m
     }
@@ -2479,6 +2668,86 @@ mod tests {
         assert_eq!(report.lifecycle_transition.failed, 1);
     }
 
+    #[tokio::test]
+    async fn report_derives_scanner_maintenance_control_status() {
+        let metrics = Metrics::new();
+        let start = metrics.start_scan_cycle_work();
+        metrics.record_scanner_source_checked(ScannerWorkSource::Usage, 3);
+        metrics.record_scanner_source_missed(ScannerWorkSource::Lifecycle, 2);
+        metrics.record_scanner_source_queued(ScannerWorkSource::BucketReplication, 1);
+        metrics.record_scan_cycle_partial_with_source(
+            Duration::from_secs(5),
+            ScanCyclePartialReason::Objects,
+            Some(ScannerWorkSource::Usage),
+        );
+        metrics.record_scanner_lifecycle_transition_state(ScannerLifecycleTransitionStateUpdate {
+            queue_capacity: 4,
+            queued: 2,
+            queue_full: 1,
+            ..Default::default()
+        });
+
+        let report = metrics.report().await;
+
+        assert_eq!(report.maintenance_control.primary_control, "blocked_source");
+        let usage = report
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == ScannerWorkSource::Usage.as_str())
+            .expect("usage source control should be visible");
+        assert_eq!(usage.state, "deferred");
+        assert_eq!(usage.reason, "partial_cycle");
+        assert_eq!(usage.current_checked, 3);
+        assert_eq!(usage.partial_cycles, 1);
+
+        let lifecycle = report
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == ScannerWorkSource::Lifecycle.as_str())
+            .expect("lifecycle source control should be visible");
+        assert_eq!(lifecycle.state, "blocked");
+        assert_eq!(lifecycle.reason, "missed_work");
+        assert_eq!(lifecycle.current_missed, 2);
+        assert_eq!(lifecycle.backlog, 2);
+
+        let bucket_replication = report
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == ScannerWorkSource::BucketReplication.as_str())
+            .expect("bucket replication source control should be visible");
+        assert_eq!(bucket_replication.state, "active");
+        assert_eq!(bucket_replication.reason, "queued_work");
+        assert_eq!(bucket_replication.current_queued, 1);
+
+        metrics.finish_scan_cycle_work(start);
+    }
+
+    #[tokio::test]
+    async fn report_uses_last_cycle_source_work_for_maintenance_control_between_cycles() {
+        let metrics = Metrics::new();
+        let start = metrics.start_scan_cycle_work();
+        metrics.record_scanner_source_missed(ScannerWorkSource::Lifecycle, 2);
+
+        metrics.finish_scan_cycle_work(start);
+        let report = metrics.report().await;
+
+        assert!(report.current_cycle_source_work.is_empty());
+        let lifecycle = report
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == ScannerWorkSource::Lifecycle.as_str())
+            .expect("lifecycle source control should be visible");
+        assert_eq!(report.maintenance_control.primary_control, "blocked_source");
+        assert_eq!(lifecycle.state, "blocked");
+        assert_eq!(lifecycle.reason, "missed_work");
+        assert_eq!(lifecycle.current_missed, 2);
+        assert_eq!(lifecycle.backlog, 2);
+    }
+
     #[tokio::test]
     async fn scanner_metrics_update_source_work() {
         let metrics = Metrics::new();

crates/ecstore/src/metrics_realtime.rs

@@ -19,7 +19,9 @@ use rustfs_io_metrics::internode_metrics::global_internode_metrics;
 use rustfs_madmin::metrics::{
     DiskIOStats, DiskMetric, LastMinute as MadminLastMinute, NetDevLine, NetMetrics, RPCMetrics, RealtimeMetrics,
     ScannerCheckpointReport as MadminScannerCheckpointReport,
-    ScannerLifecycleTransitionSnapshot as MadminScannerLifecycleTransitionSnapshot, ScannerMetrics as MadminScannerMetrics,
+    ScannerLifecycleTransitionSnapshot as MadminScannerLifecycleTransitionSnapshot,
+    ScannerMaintenanceControlSnapshot as MadminScannerMaintenanceControlSnapshot,
+    ScannerMaintenanceSourceSnapshot as MadminScannerMaintenanceSourceSnapshot, ScannerMetrics as MadminScannerMetrics,
     ScannerPacingPressureSnapshot as MadminScannerPacingPressureSnapshot,
     ScannerSourceCycleSnapshot as MadminScannerSourceCycleSnapshot, ScannerSourceWorkSnapshot as MadminScannerSourceWorkSnapshot,
     TimedAction as MadminTimedAction,
@@ -177,6 +179,25 @@ fn to_madmin_scanner_metrics(metrics: rustfs_common::metrics::ScannerMetricsRepo
             completed: metrics.lifecycle_transition.completed,
             failed: metrics.lifecycle_transition.failed,
         },
+        maintenance_control: MadminScannerMaintenanceControlSnapshot {
+            primary_control: metrics.maintenance_control.primary_control,
+            sources: metrics
+                .maintenance_control
+                .sources
+                .into_iter()
+                .map(|source| MadminScannerMaintenanceSourceSnapshot {
+                    source: source.source,
+                    state: source.state,
+                    reason: source.reason,
+                    backlog: source.backlog,
+                    current_checked: source.current_checked,
+                    current_queued: source.current_queued,
+                    current_missed: source.current_missed,
+                    lifetime_missed: source.lifetime_missed,
+                    partial_cycles: source.partial_cycles,
+                })
+                .collect(),
+        },
         partial_cycles_by_source: metrics
             .partial_cycles_by_source
             .into_iter()
@@ -580,6 +601,43 @@ mod test {
         assert_eq!(scanner.last_cycle_lifecycle_transition_actions, 7);
     }
 
+    #[test]
+    fn scanner_metrics_mapping_preserves_maintenance_control_status() {
+        let scanner = to_madmin_scanner_metrics(rustfs_common::metrics::ScannerMetricsReport {
+            maintenance_control: rustfs_common::metrics::ScannerMaintenanceControlSnapshot {
+                primary_control: "blocked_source".to_string(),
+                sources: vec![rustfs_common::metrics::ScannerMaintenanceSourceSnapshot {
+                    source: "lifecycle".to_string(),
+                    state: "blocked".to_string(),
+                    reason: "missed_work".to_string(),
+                    backlog: 4,
+                    current_checked: 2,
+                    current_queued: 1,
+                    current_missed: 3,
+                    lifetime_missed: 8,
+                    partial_cycles: 5,
+                }],
+            },
+            ..Default::default()
+        });
+
+        assert_eq!(scanner.maintenance_control.primary_control, "blocked_source");
+        let lifecycle = scanner
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == "lifecycle")
+            .expect("lifecycle maintenance control should be mapped");
+        assert_eq!(lifecycle.state, "blocked");
+        assert_eq!(lifecycle.reason, "missed_work");
+        assert_eq!(lifecycle.backlog, 4);
+        assert_eq!(lifecycle.current_checked, 2);
+        assert_eq!(lifecycle.current_queued, 1);
+        assert_eq!(lifecycle.current_missed, 3);
+        assert_eq!(lifecycle.lifetime_missed, 8);
+        assert_eq!(lifecycle.partial_cycles, 5);
+    }
+
     #[test]
     fn scanner_metrics_mapping_preserves_distributed_status_fields() {
         let scanner = to_madmin_scanner_metrics(rustfs_common::metrics::ScannerMetricsReport {

crates/madmin/src/metrics.rs

@@ -158,6 +158,108 @@ pub struct ScannerSourceWorkSnapshot {
     pub missed: u64,
 }
 
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ScannerMaintenanceSourceSnapshot {
+    #[serde(rename = "source", default)]
+    pub source: String,
+    #[serde(rename = "state", default)]
+    pub state: String,
+    #[serde(rename = "reason", default)]
+    pub reason: String,
+    #[serde(rename = "backlog", default)]
+    pub backlog: u64,
+    #[serde(rename = "current_checked", default)]
+    pub current_checked: u64,
+    #[serde(rename = "current_queued", default)]
+    pub current_queued: u64,
+    #[serde(rename = "current_missed", default)]
+    pub current_missed: u64,
+    #[serde(rename = "lifetime_missed", default)]
+    pub lifetime_missed: u64,
+    #[serde(rename = "partial_cycles", default)]
+    pub partial_cycles: u64,
+}
+
+impl ScannerMaintenanceSourceSnapshot {
+    fn merge(&mut self, other: &Self) {
+        if scanner_maintenance_state_priority(&other.state) > scanner_maintenance_state_priority(&self.state) {
+            self.state = other.state.clone();
+            self.reason = other.reason.clone();
+        } else if self.reason.is_empty() || self.reason == SCANNER_MAINTENANCE_REASON_IDLE {
+            self.reason = other.reason.clone();
+        }
+
+        self.backlog = self.backlog.saturating_add(other.backlog);
+        self.current_checked = self.current_checked.saturating_add(other.current_checked);
+        self.current_queued = self.current_queued.saturating_add(other.current_queued);
+        self.current_missed = self.current_missed.saturating_add(other.current_missed);
+        self.lifetime_missed = self.lifetime_missed.saturating_add(other.lifetime_missed);
+        self.partial_cycles = self.partial_cycles.saturating_add(other.partial_cycles);
+    }
+}
+
+const SCANNER_MAINTENANCE_CONTROL_NONE: &str = "none";
+const SCANNER_MAINTENANCE_REASON_IDLE: &str = "idle";
+
+fn scanner_maintenance_state_priority(state: &str) -> u8 {
+    match state {
+        "blocked" => 3,
+        "deferred" => 2,
+        "active" => 1,
+        _ => 0,
+    }
+}
+
+fn scanner_maintenance_control_priority(control: &str) -> u8 {
+    match control {
+        "blocked_source" => 4,
+        "deferred_source" => 3,
+        "active_source" => 2,
+        "pacing_pressure" => 1,
+        _ => 0,
+    }
+}
+
+fn default_scanner_maintenance_control() -> String {
+    SCANNER_MAINTENANCE_CONTROL_NONE.to_string()
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ScannerMaintenanceControlSnapshot {
+    #[serde(rename = "primary_control", default = "default_scanner_maintenance_control")]
+    pub primary_control: String,
+    #[serde(rename = "sources", default)]
+    pub sources: Vec<ScannerMaintenanceSourceSnapshot>,
+}
+
+impl Default for ScannerMaintenanceControlSnapshot {
+    fn default() -> Self {
+        Self {
+            primary_control: default_scanner_maintenance_control(),
+            sources: Vec::new(),
+        }
+    }
+}
+
+impl ScannerMaintenanceControlSnapshot {
+    fn merge(&mut self, other: &Self) {
+        if scanner_maintenance_control_priority(&other.primary_control)
+            > scanner_maintenance_control_priority(&self.primary_control)
+        {
+            self.primary_control = other.primary_control.clone();
+        }
+
+        for source in other.sources.iter() {
+            if let Some(existing) = self.sources.iter_mut().find(|existing| existing.source == source.source) {
+                existing.merge(source);
+            } else {
+                self.sources.push(source.clone());
+            }
+        }
+        self.sources.sort_by(|left, right| left.source.cmp(&right.source));
+    }
+}
+
 impl ScannerSourceWorkSnapshot {
     fn merge(&mut self, other: &Self) {
         self.checked = self.checked.saturating_add(other.checked);
@@ -424,6 +526,8 @@ pub struct ScannerMetrics {
     pub pacing_pressure: ScannerPacingPressureSnapshot,
     #[serde(rename = "lifecycle_transition", default)]
     pub lifecycle_transition: ScannerLifecycleTransitionSnapshot,
+    #[serde(rename = "maintenance_control", default)]
+    pub maintenance_control: ScannerMaintenanceControlSnapshot,
     #[serde(rename = "throttle_idle_mode_enabled", default)]
     pub throttle_idle_mode_enabled: bool,
     #[serde(rename = "throttle_sleep_factor", default)]
@@ -496,6 +600,7 @@ impl ScannerMetrics {
         self.oldest_active_path_age_seconds = self.oldest_active_path_age_seconds.max(other.oldest_active_path_age_seconds);
         self.pacing_pressure.merge(&other.pacing_pressure);
         self.lifecycle_transition.merge(&other.lifecycle_transition);
+        self.maintenance_control.merge(&other.maintenance_control);
         self.current_set_scan_concurrency_limit = self
             .current_set_scan_concurrency_limit
             .saturating_add(other.current_set_scan_concurrency_limit);
@@ -1307,6 +1412,87 @@ mod tests {
         assert_eq!(scanner.last_cycle_lifecycle_transition_actions, 26);
     }
 
+    #[test]
+    fn scanner_metrics_merge_aggregates_maintenance_control_status() {
+        let collected_at = Utc::now();
+        let mut scanner = ScannerMetrics {
+            collected_at,
+            maintenance_control: ScannerMaintenanceControlSnapshot {
+                primary_control: "active_source".to_string(),
+                sources: vec![ScannerMaintenanceSourceSnapshot {
+                    source: "usage".to_string(),
+                    state: "active".to_string(),
+                    reason: "active_work".to_string(),
+                    backlog: 1,
+                    current_checked: 2,
+                    current_queued: 0,
+                    current_missed: 0,
+                    lifetime_missed: 0,
+                    partial_cycles: 0,
+                }],
+            },
+            ..Default::default()
+        };
+
+        scanner.merge(&ScannerMetrics {
+            collected_at: collected_at + chrono::Duration::seconds(1),
+            maintenance_control: ScannerMaintenanceControlSnapshot {
+                primary_control: "blocked_source".to_string(),
+                sources: vec![
+                    ScannerMaintenanceSourceSnapshot {
+                        source: "usage".to_string(),
+                        state: "deferred".to_string(),
+                        reason: "partial_cycle".to_string(),
+                        backlog: 3,
+                        current_checked: 5,
+                        current_queued: 1,
+                        current_missed: 0,
+                        lifetime_missed: 0,
+                        partial_cycles: 2,
+                    },
+                    ScannerMaintenanceSourceSnapshot {
+                        source: "lifecycle".to_string(),
+                        state: "blocked".to_string(),
+                        reason: "missed_work".to_string(),
+                        backlog: 4,
+                        current_checked: 0,
+                        current_queued: 0,
+                        current_missed: 4,
+                        lifetime_missed: 9,
+                        partial_cycles: 1,
+                    },
+                ],
+            },
+            ..Default::default()
+        });
+
+        assert_eq!(scanner.maintenance_control.primary_control, "blocked_source");
+        let lifecycle = scanner
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == "lifecycle")
+            .expect("lifecycle maintenance control should be present");
+        assert_eq!(lifecycle.state, "blocked");
+        assert_eq!(lifecycle.reason, "missed_work");
+        assert_eq!(lifecycle.backlog, 4);
+        assert_eq!(lifecycle.current_missed, 4);
+        assert_eq!(lifecycle.lifetime_missed, 9);
+
+        let usage = scanner
+            .maintenance_control
+            .sources
+            .iter()
+            .find(|source| source.source == "usage")
+            .expect("usage maintenance control should be present");
+        assert_eq!(usage.state, "deferred");
+        assert_eq!(usage.reason, "partial_cycle");
+        assert_eq!(usage.backlog, 4);
+        assert_eq!(usage.current_checked, 7);
+        assert_eq!(usage.current_queued, 1);
+        assert_eq!(usage.partial_cycles, 2);
+    }
+
     #[test]
     fn scanner_metrics_merge_preserves_distributed_status_fields() {
         let collected_at = Utc::now();

docs/operations/scanner-benchmark-runbook.md

@@ -282,6 +282,8 @@ Compare these fields between baseline and tuned runs:
 | `runtime_config.*.value` and `runtime_config.*.source` | Confirms the tested settings actually took effect. |
 | `metrics.pacing_pressure.primary_pressure` | Shows whether pressure is from queues, budgets, pause activity, active scans, or no scanner pressure. |
 | `metrics.pacing_pressure.last_cycle_total_pause_ratio` | Shows how much of the last cycle was cooperative scanner pause time. |
+| `metrics.maintenance_control.primary_control` | Shows whether source-level maintenance is blocked, deferred, active, only pacing-limited, or idle. |
+| `metrics.maintenance_control.sources` | Shows the source, state, reason, backlog, current or last-cycle missed work, and partial-cycle count for each scanner maintenance source. |
 | `metrics.current_cycle_objects_scanned` | Confirms object scan progress during the current cycle. |
 | `metrics.current_cycle_directories_scanned` | Confirms directory walk progress during the current cycle. |
 | `metrics.last_cycle_result` | Confirms whether the previous cycle completed, stopped partially, or failed. |

docs/operations/scanner-runtime-controls.md

@@ -97,6 +97,7 @@ metrics.pacing_pressure.primary_pressure
 metrics.pacing_pressure.last_cycle_budget_limited
 metrics.lifecycle_transition.current_queued
 metrics.lifecycle_transition.scanner_missed
+metrics.maintenance_control.primary_control
 metrics.source_work
 metrics.scan_checkpoint
 ```
@@ -146,6 +147,45 @@ Use these counters to decide whether scan progress is limited by scanner pacing
 or by a downstream subsystem such as lifecycle transition, replication repair,
 or heal admission.
 
+## Reading Maintenance Control
+
+`metrics.maintenance_control` derives a source-level control snapshot from
+scanner pacing, partial-cycle state, source work, and lifecycle transition
+queue state. It does not change scanner scheduling by itself; it explains why a
+source is moving, deferred, or blocked. When no scan cycle is currently active,
+source-work controls use the last completed cycle so recently missed work stays
+visible between scanner passes.
+
+`metrics.maintenance_control.primary_control` summarizes the highest-priority
+source state:
+
+| Value | Meaning |
+|---|---|
+| `blocked_source` | At least one maintenance source found work that could not be admitted or is blocked by a downstream queue. |
+| `deferred_source` | At least one source was deferred by a partial scanner cycle or budget-limited pass. |
+| `active_source` | At least one source has current-cycle work or queued downstream work. |
+| `pacing_pressure` | No source-specific state dominated, but scanner pacing pressure is still visible. |
+| `none` | No source-level maintenance control pressure was observed. |
+
+Each `metrics.maintenance_control.sources[]` entry has:
+
+| Field | Meaning |
+|---|---|
+| `source` | Scanner source such as `usage`, `lifecycle`, `bucket_replication`, `site_replication`, `heal`, `bitrot`, or `alerts`. |
+| `state` | `idle`, `active`, `deferred`, or `blocked`. |
+| `reason` | Derived reason such as `active_work`, `queued_work`, `partial_cycle`, `missed_work`, `transition_queue_backlog`, or `transition_queue_full`. |
+| `backlog` | Current source-level backlog estimate from queued or missed work. |
+| `current_checked` | Current-cycle checked work for this source, or the last completed cycle when no scan cycle is active. |
+| `current_queued` | Current-cycle queued work for this source, or the last completed cycle when no scan cycle is active. |
+| `current_missed` | Current-cycle work that could not be admitted, or the last completed cycle when no scan cycle is active. |
+| `lifetime_missed` | Lifetime missed work counter for context. |
+| `partial_cycles` | Partial cycles attributed to this source. |
+
+Use this snapshot before changing scanner controls. For example,
+`blocked_source` with `lifecycle/missed_work` points at downstream lifecycle
+admission, while `deferred_source` with `usage/partial_cycle` points at scanner
+cycle budgets.
+
 ## Reading Distributed Metrics
 
 `/rustfs/admin/v3/scanner/status` and `/rustfs/admin/v3/metrics` report the
@@ -169,11 +209,12 @@ done
 ```
 
 The `aggregated.scanner` payload preserves the same scanner progress,
-checkpoint, pacing, source work, and lifecycle transition fields used by the
+checkpoint, pacing, source work, maintenance control, and lifecycle transition
-local scanner status, but only for the node that returned the response. The
+fields used by the local scanner status, but only for the node that returned
-`by_host.*.scanner` payload keeps that node's host view. Compare the per-node
+the response. The `by_host.*.scanner` payload keeps that node's host view.
-artifacts externally to find old active paths, partial checkpoints, pacing
+Compare the per-node artifacts externally to find old active paths, partial
-pressure, or downstream queue admission problems across the deployment.
+checkpoints, pacing pressure, source-level control pressure, or downstream
+queue admission problems across the deployment.
 
 ## Reading Lifecycle Transition Status
 
@@ -206,21 +247,23 @@ sustained CPU usage while the scanner is enabled:
 
 1. Read `/v3/scanner/status`.
 2. Check `metrics.pacing_pressure.primary_pressure`.
-3. Check `runtime_config.delay`, `runtime_config.max_wait_seconds`, and
+3. Check `metrics.maintenance_control.primary_control` and source entries
+   before changing runtime controls.
+4. Check `runtime_config.delay`, `runtime_config.max_wait_seconds`, and
    `runtime_config.cycle_interval_seconds` to confirm the active values and
    their sources.
-4. Check `metrics.current_cycle_objects_scanned`,
+5. Check `metrics.current_cycle_objects_scanned`,
    `metrics.current_cycle_directories_scanned`, and active paths to confirm the
    scanner is the active work.
-5. If `primary_pressure` is `throttle_pause` and pause ratios are low, raise
+6. If `primary_pressure` is `throttle_pause` and pause ratios are low, raise
    `scanner.delay` first.
-6. If individual sleeps are too short, raise `scanner.max_wait`.
+7. If individual sleeps are too short, raise `scanner.max_wait`.
-7. If each scan cycle finishes but starts too often, raise `scanner.cycle`.
+8. If each scan cycle finishes but starts too often, raise `scanner.cycle`.
-8. If scans must be broken into bounded chunks, set one of the cycle budgets:
+9. If scans must be broken into bounded chunks, set one of the cycle budgets:
    `scanner.cycle_max_duration`, `scanner.cycle_max_objects`, or
    `scanner.cycle_max_directories`.
-9. Recheck `pacing_pressure`, source work, and lifecycle transition status after
+10. Recheck `pacing_pressure`, `maintenance_control`, source work, and
-   one or more scanner cycles.
+    lifecycle transition status after one or more scanner cycles.
 
 Do not rely only on a longer cycle interval if lifecycle, replication, heal, or
 bitrot work must keep moving. Use source work and transition status to confirm