DAOS-16477 mgmt: return suspect engines for pool healthy query (#15458)

* DAOS-16477 mgmt: return suspect engines for pool healthy query

After significant failures, the system may leave behind some suspect
engines that were marked as DEAD by the SWIM protocol, but were not
excluded from the system to prevent data loss. An administrator
can bring these ranks back online by restarting them.

This PR aims to provide an administrative interface for querying
suspect engines following a massive failure. These suspect engines
can be retrieved using the daos/dmg --health-only command.

An example of output of dmg pool query --health-only:

Pool 6f450a68-8c7d-4da9-8900-02691650f6a2, ntarget=8, disabled=2, leader=3, version=4, state=Degraded
Pool health info:
- Disabled ranks: 1
- Suspect ranks: 2
- Rebuild busy, 0 objs, 0 recs

Features: DmgPoolQueryRanks
Signed-off-by: Wang Shilong <[email protected]>
Signed-off-by: Phil Henderson <[email protected]>
Co-authored-by: Phil Henderson <[email protected]>

docs/admin/pool_operations.md

@@ -286,6 +286,28 @@ The example below shows a rebuild in progress and NVMe space allocated.
     Rebuild busy, 75 objs, 9722 recs
 ```
 
+After experiencing significant failures, the pool may retain some suspect
+engines that have been marked as DEAD by the SWIM protocol but were not excluded
+from the pool to prevent potential data inconsistency. An administrator can bring
+these engines back online by restarting them. The example below illustrates the
+system’s status with suspect and disabled engines.
+
+```bash
+$ dmg pool query tank -t
+```
+
+NB: The --health-only/-t option is necessary to conduct pool health-related queries only.
+This is important because suspect ranks may cause commands to hang and timeout so identifying
+and restarting them is a useful procedure.
+
+```bash
+Pool 6f450a68-8c7d-4da9-8900-02691650f6a2, ntarget=8, disabled=2, leader=3, version=4, state=Degraded
+    Pool health info:
+    - Disabled ranks: 1
+    - Suspect ranks: 2
+    - Rebuild busy, 0 objs, 0 recs
+```
+
 Additional status and telemetry data is planned to be exported through
 management tools and will be documented here once available.
 

src/control/cmd/daos/health.go

@@ -99,24 +99,19 @@ func (cmd *healthCheckCmd) Execute([]string) error {
 			}
 		}()
 
-		queryMask := daos.MustNewPoolQueryMask(daos.PoolQueryOptionEnabledEngines)
+		queryMask := daos.MustNewPoolQueryMask(daos.PoolQueryOptionEnabledEngines,
+			daos.PoolQueryOptionSuspectEngines)
+		if pool.DisabledTargets > 0 {
+			queryMask.SetOptions(daos.PoolQueryOptionDisabledEngines)
+		}
 		tpi, err := queryPool(poolHdl, queryMask)
 		if err != nil {
 			cmd.Errorf("failed to query pool %s: %v", pool.Label, err)
 			continue
 		}
 		pool.EnabledRanks = tpi.EnabledRanks
-
-		if pool.DisabledTargets > 0 {
-			queryMask.ClearAll()
-			queryMask.SetOptions(daos.PoolQueryOptionDisabledEngines)
-			tpi, err = queryPool(poolHdl, queryMask)
-			if err != nil {
-				cmd.Errorf("failed to query pool %s: %v", pool.Label, err)
-				continue
-			}
-			pool.DisabledRanks = tpi.DisabledRanks
-		}
+		pool.DisabledRanks = tpi.DisabledRanks
+		pool.SuspectRanks = tpi.SuspectRanks
 
 		poolConts, err := listContainers(poolHdl)
 		if err != nil {

src/control/cmd/daos/pool.go

@@ -296,11 +296,12 @@ func convertPoolInfo(pinfo *C.daos_pool_info_t) (*daos.PoolInfo, error) {
 	return poolInfo, nil
 }
 
-func queryPool(poolHdl C.daos_handle_t, queryMask daos.PoolQueryMask) (*daos.PoolInfo, error) {
+func queryPoolRankLists(poolHdl C.daos_handle_t, queryMask daos.PoolQueryMask) (*daos.PoolInfo, error) {
 	var rlPtr **C.d_rank_list_t = nil
 	var rl *C.d_rank_list_t = nil
 
-	if queryMask.HasOption(daos.PoolQueryOptionEnabledEngines) || queryMask.HasOption(daos.PoolQueryOptionDisabledEngines) {
+	if queryMask.HasOption(daos.PoolQueryOptionEnabledEngines) || queryMask.HasOption(daos.PoolQueryOptionDisabledEngines) ||
+		queryMask.HasOption(daos.PoolQueryOptionSuspectEngines) {
 		rlPtr = &rl
 	}
 
@@ -330,6 +331,68 @@ func queryPool(poolHdl C.daos_handle_t, queryMask daos.PoolQueryMask) (*daos.Poo
 		if queryMask.HasOption(daos.PoolQueryOptionDisabledEngines) {
 			poolInfo.DisabledRanks = rs
 		}
+		if queryMask.HasOption(daos.PoolQueryOptionSuspectEngines) {
+			poolInfo.SuspectRanks = rs
+		}
+	}
+
+	return poolInfo, nil
+}
+func queryPool(poolHdl C.daos_handle_t, queryMask daos.PoolQueryMask) (*daos.PoolInfo, error) {
+	poolInfo := &daos.PoolInfo{}
+	originalMask := queryMask // Save the original queryMask
+
+	// Function to handle the query and return a single RankList
+	queryAndUpdate := func(option string) error {
+		// Clear previous options and set new option
+		queryMask.ClearAll()
+		queryMask.SetOptions(option)
+
+		poolInfo1, err := queryPoolRankLists(poolHdl, queryMask)
+		if err != nil {
+			return err
+		}
+
+		switch option {
+		case daos.PoolQueryOptionEnabledEngines:
+			poolInfo.EnabledRanks = poolInfo1.EnabledRanks
+		case daos.PoolQueryOptionDisabledEngines:
+			poolInfo.DisabledRanks = poolInfo1.DisabledRanks
+		case daos.PoolQueryOptionSuspectEngines:
+			poolInfo.SuspectRanks = poolInfo1.SuspectRanks
+		}
+		return nil
+	}
+
+	// Preprocess queryMask, select one option for the first query
+	var firstOption string
+	if originalMask.HasOption(daos.PoolQueryOptionEnabledEngines) {
+		firstOption = daos.PoolQueryOptionEnabledEngines
+	} else if originalMask.HasOption(daos.PoolQueryOptionDisabledEngines) {
+		firstOption = daos.PoolQueryOptionDisabledEngines
+	} else if originalMask.HasOption(daos.PoolQueryOptionSuspectEngines) {
+		firstOption = daos.PoolQueryOptionSuspectEngines
+	}
+
+	// Perform the first query to get basic information
+	if err := queryAndUpdate(firstOption); err != nil {
+		return nil, err
+	}
+
+	// Check the original query mask and update fields as needed
+	queryOptions := []string{
+		daos.PoolQueryOptionEnabledEngines,
+		daos.PoolQueryOptionDisabledEngines,
+		daos.PoolQueryOptionSuspectEngines,
+	}
+
+	// Process each option sequentially
+	for _, opt := range queryOptions {
+		if originalMask.HasOption(opt) && opt != firstOption {
+			if err := queryAndUpdate(opt); err != nil {
+				return nil, err
+			}
+		}
 	}
 
 	return poolInfo, nil

src/control/cmd/daos/pretty/health.go

@@ -61,6 +61,13 @@ func printPoolHealth(out io.Writer, pi *daos.PoolInfo, verbose bool) {
 	}
 
 	var healthStrings []string
+	if pi.SuspectRanks != nil && pi.SuspectRanks.Count() > 0 {
+		degStr := "Suspect"
+		if verbose {
+			degStr += fmt.Sprintf(" %s", pi.SuspectRanks)
+		}
+		healthStrings = append(healthStrings, degStr)
+	}
 	if pi.DisabledTargets > 0 {
 		degStr := "Degraded"
 		if verbose {

src/control/cmd/daos/pretty/pool.go

@@ -53,6 +53,10 @@ func PrintPoolInfo(pi *daos.PoolInfo, out io.Writer) error {
 	if pi.DisabledRanks != nil && pi.DisabledRanks.Count() > 0 {
 		fmt.Fprintf(w, "- Disabled ranks: %s\n", pi.DisabledRanks)
 	}
+	if pi.QueryMask.HasOption(daos.PoolQueryOptionSuspectEngines) &&
+		pi.SuspectRanks != nil && pi.SuspectRanks.Count() > 0 {
+		fmt.Fprintf(w, "- Suspect ranks: %s\n", pi.SuspectRanks)
+	}
 	if pi.Rebuild != nil {
 		if pi.Rebuild.Status == 0 {
 			fmt.Fprintf(w, "- Rebuild %s, %d objs, %d recs\n",

src/control/cmd/daos/pretty/pool_test.go

@@ -122,6 +122,45 @@ Pool space info:
 - Storage tier 1 (NVMe):
   Total size: 2 B
   Free: 1 B, min:0 B, max:0 B, mean:0 B
+`, poolUUID.String()),
+		},
+		"normal response; suspect ranks": {
+			pi: &daos.PoolInfo{
+				QueryMask:        daos.HealthOnlyPoolQueryMask,
+				State:            daos.PoolServiceStateDegraded,
+				UUID:             poolUUID,
+				TotalTargets:     2,
+				DisabledTargets:  1,
+				ActiveTargets:    1,
+				ServiceLeader:    42,
+				Version:          100,
+				PoolLayoutVer:    1,
+				UpgradeLayoutVer: 2,
+				DisabledRanks:    ranklist.MustCreateRankSet("[0,1,3]"),
+				SuspectRanks:     ranklist.MustCreateRankSet("[2]"),
+				Rebuild: &daos.PoolRebuildStatus{
+					State:   daos.PoolRebuildStateBusy,
+					Objects: 42,
+					Records: 21,
+				},
+				TierStats: []*daos.StorageUsageStats{
+					{
+						Total: 2,
+						Free:  1,
+					},
+					{
+						Total: 2,
+						Free:  1,
+					},
+				},
+			},
+			expPrintStr: fmt.Sprintf(`
+Pool %s, ntarget=2, disabled=1, leader=42, version=100, state=Degraded
+Pool layout out of date (1 < 2) -- see `+backtickStr+` for details.
+Pool health info:
+- Disabled ranks: 0-1,3
+- Suspect ranks: 2
+- Rebuild busy, 42 objs, 21 recs
 `, poolUUID.String()),
 		},
 		"normal response; disabled ranks": {