shell: volume.fix.replication also purge over replicated volumes

weed/shell/command_volume_fix_replication.go

@@ -3,8 +3,8 @@ package shell
 import (
 	"context"
 	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/storage/needle"
 	"io"
-	"math/rand"
 	"sort"
 
 	"github.com/chrislusf/seaweedfs/weed/operation"
@@ -27,11 +27,13 @@ func (c *commandVolumeFixReplication) Name() string {
 func (c *commandVolumeFixReplication) Help() string {
 	return `add replicas to volumes that are missing replicas
 
-	This command finds all under-replicated volumes, and finds volume servers with free slots.
+	This command finds all over-replicated volumes. If found, it will purge the oldest copies and stop.
+
+	This command also finds all under-replicated volumes, and finds volume servers with free slots.
 	If the free slots satisfy the replication requirement, the volume content is copied over and mounted.
 
 	volume.fix.replication -n # do not take action
-	volume.fix.replication    # actually copying the volume files and mount the volume
+	volume.fix.replication    # actually deleting or copying the volume files and mount the volume
 
 	Note:
 		* each time this will only add back one replica for one volume id. If there are multiple replicas
@@ -69,12 +71,10 @@ func (c *commandVolumeFixReplication) Do(args []string, commandEnv *CommandEnv,
 	eachDataNode(resp.TopologyInfo, func(dc string, rack RackId, dn *master_pb.DataNodeInfo) {
 		loc := newLocation(dc, string(rack), dn)
 		for _, v := range dn.VolumeInfos {
-			if v.ReplicaPlacement > 0 {
-				volumeReplicas[v.Id] = append(volumeReplicas[v.Id], &VolumeReplica{
-					location: &loc,
-					info:     v,
-				})
-			}
+			volumeReplicas[v.Id] = append(volumeReplicas[v.Id], &VolumeReplica{
+				location: &loc,
+				info:     v,
+			})
 		}
 		allLocations = append(allLocations, loc)
 	})
@@ -82,7 +82,7 @@ func (c *commandVolumeFixReplication) Do(args []string, commandEnv *CommandEnv,
 	// find all under replicated volumes
 	var underReplicatedVolumeIds, overReplicatedVolumeIds []uint32
 	for vid, replicas := range volumeReplicas {
-		replica := replicas[rand.Intn(len(replicas))]
+		replica := replicas[0]
 		replicaPlacement, _ := super_block.NewReplicaPlacementFromByte(byte(replica.info.ReplicaPlacement))
 		if replicaPlacement.GetCopyCount() > len(replicas) {
 			underReplicatedVolumeIds = append(underReplicatedVolumeIds, vid)
@@ -92,6 +92,10 @@ func (c *commandVolumeFixReplication) Do(args []string, commandEnv *CommandEnv,
 		}
 	}
 
+	if len(overReplicatedVolumeIds) > 0 {
+		return c.fixOverReplicatedVolumes(commandEnv, writer, takeAction, overReplicatedVolumeIds, volumeReplicas, allLocations)
+	}
+
 	if len(underReplicatedVolumeIds) == 0 {
 		return fmt.Errorf("no under replicated volumes")
 	}
@@ -107,10 +111,31 @@ func (c *commandVolumeFixReplication) Do(args []string, commandEnv *CommandEnv,
 
 }
 
+func (c *commandVolumeFixReplication) fixOverReplicatedVolumes(commandEnv *CommandEnv, writer io.Writer, takeAction bool, overReplicatedVolumeIds []uint32, volumeReplicas map[uint32][]*VolumeReplica, allLocations []location) error {
+	for _, vid := range overReplicatedVolumeIds {
+		replicas := volumeReplicas[vid]
+		replicaPlacement, _ := super_block.NewReplicaPlacementFromByte(byte(replicas[0].info.ReplicaPlacement))
+
+		replica := pickOneReplicaToDelete(replicas, replicaPlacement)
+
+		fmt.Fprintf(writer, "deleting volume %d from %s ...\n", replica.info.Id, replica.location.dataNode.Id)
+
+		if !takeAction {
+			break
+		}
+
+		if err := deleteVolume(commandEnv.option.GrpcDialOption, needle.VolumeId(replica.info.Id), replica.location.dataNode.Id); err != nil {
+			return fmt.Errorf("deleting volume %d from %s : %v", replica.info.Id, replica.location.dataNode.Id, err)
+		}
+
+	}
+	return nil
+}
+
 func (c *commandVolumeFixReplication) fixUnderReplicatedVolumes(commandEnv *CommandEnv, writer io.Writer, takeAction bool, underReplicatedVolumeIds []uint32, volumeReplicas map[uint32][]*VolumeReplica, allLocations []location) error {
 	for _, vid := range underReplicatedVolumeIds {
 		replicas := volumeReplicas[vid]
-		replica := replicas[rand.Intn(len(replicas))]
+		replica := pickOneReplicaToCopyFrom(replicas)
 		replicaPlacement, _ := super_block.NewReplicaPlacementFromByte(byte(replica.info.ReplicaPlacement))
 		foundNewLocation := false
 		for _, dst := range allLocations {
@@ -191,20 +216,13 @@ func keepDataNodesSorted(dataNodes []location) {
 */
 func satisfyReplicaPlacement(replicaPlacement *super_block.ReplicaPlacement, replicas []*VolumeReplica, possibleLocation location) bool {
 
-	existingDataNodes := make(map[string]int)
-	for _, replica := range replicas {
-		existingDataNodes[replica.location.String()] += 1
-	}
-	sameDataNodeCount := existingDataNodes[possibleLocation.String()]
-	// avoid duplicated volume on the same data node
-	if sameDataNodeCount > 0 {
+	existingDataCenters, _, existingDataNodes := countReplicas(replicas)
+
+	if _, found := existingDataNodes[possibleLocation.String()]; found {
+		// avoid duplicated volume on the same data node
 		return false
 	}
 
-	existingDataCenters := make(map[string]int)
-	for _, replica := range replicas {
-		existingDataCenters[replica.location.DataCenter()] += 1
-	}
 	primaryDataCenters, _ := findTopKeys(existingDataCenters)
 
 	// ensure data center count is within limit
@@ -225,20 +243,20 @@ func satisfyReplicaPlacement(replicaPlacement *super_block.ReplicaPlacement, rep
 	}
 
 	// now this is one of the primary dcs
-	existingRacks := make(map[string]int)
+	primaryDcRacks := make(map[string]int)
 	for _, replica := range replicas {
 		if replica.location.DataCenter() != possibleLocation.DataCenter() {
 			continue
 		}
-		existingRacks[replica.location.Rack()] += 1
+		primaryDcRacks[replica.location.Rack()] += 1
 	}
-	primaryRacks, _ := findTopKeys(existingRacks)
-	sameRackCount := existingRacks[possibleLocation.Rack()]
+	primaryRacks, _ := findTopKeys(primaryDcRacks)
+	sameRackCount := primaryDcRacks[possibleLocation.Rack()]
 
 	// ensure rack count is within limit
-	if _, found := existingRacks[possibleLocation.Rack()]; !found {
+	if _, found := primaryDcRacks[possibleLocation.Rack()]; !found {
 		// different from existing racks
-		if len(existingRacks) < replicaPlacement.DiffRackCount+1 {
+		if len(primaryDcRacks) < replicaPlacement.DiffRackCount+1 {
 			// lack on different racks
 			return true
 		} else {
@@ -317,3 +335,43 @@ func (l location) Rack() string {
 func (l location) DataCenter() string {
 	return l.dc
 }
+
+func pickOneReplicaToCopyFrom(replicas []*VolumeReplica) *VolumeReplica {
+	mostRecent := replicas[0]
+	for _, replica := range replicas {
+		if replica.info.ModifiedAtSecond > mostRecent.info.ModifiedAtSecond {
+			mostRecent = replica
+		}
+	}
+	return mostRecent
+}
+
+func countReplicas(replicas []*VolumeReplica) (diffDc, diffRack, diffNode map[string]int) {
+	diffDc = make(map[string]int)
+	diffRack = make(map[string]int)
+	diffNode = make(map[string]int)
+	for _, replica := range replicas {
+		diffDc[replica.location.DataCenter()] += 1
+		diffRack[replica.location.Rack()] += 1
+		diffNode[replica.location.String()] += 1
+	}
+	return
+}
+
+func pickOneReplicaToDelete(replicas []*VolumeReplica, replicaPlacement *super_block.ReplicaPlacement) *VolumeReplica {
+
+	allSame := true
+	oldest := replicas[0]
+	for _, replica := range replicas {
+		if replica.info.ModifiedAtSecond < oldest.info.ModifiedAtSecond {
+			oldest = replica
+			allSame = false
+		}
+	}
+	if !allSame {
+		return oldest
+	}
+
+	// TODO what if all the replicas have the same timestamp?
+	return oldest
+}