able to purge extra ec shard copies

weed/server/volume_grpc_erasure_coding.go

@@ -126,9 +126,21 @@ func (vs *VolumeServer) VolumeEcShardsDelete(ctx context.Context, req *volume_se
 
 	baseFilename := erasure_coding.EcShardBaseFileName(req.Collection, int(req.VolumeId))
 
+	found := false
+	for _, location := range vs.store.Locations {
+		if util.FileExists(path.Join(location.Directory, baseFilename+".ecx")) {
+			found = true
+			baseFilename = path.Join(location.Directory, baseFilename)
 			for _, shardId := range req.ShardIds {
 				os.Remove(baseFilename + erasure_coding.ToExt(int(shardId)))
 			}
+			break
+		}
+	}
+
+	if !found {
+		return nil, nil
+	}
 
 	// check whether to delete the ecx file also
 	hasEcxFile := false

weed/shell/command_ec_balance.go

@@ -129,6 +129,20 @@ func balanceEcVolumes(commandEnv *commandEnv, collection string, applyBalancing
 
 	for vid, locations := range vidLocations {
 
+		if err := doDeduplicateEcShards(ctx, commandEnv, collection, vid, locations, applyBalancing); err != nil {
+			return err
+		}
+
+		if err := doBalanceEcShards(ctx, commandEnv, collection, vid, locations, allEcNodes, applyBalancing); err != nil {
+			return err
+		}
+
+	}
+
+	return nil
+}
+
+func doBalanceEcShards(ctx context.Context, commandEnv *commandEnv, collection string, vid needle.VolumeId, locations []*EcNode, allEcNodes []*EcNode, applyBalancing bool) error {
 	// collect all ec nodes with at least one free slot
 	var possibleDestinationEcNodes []*EcNode
 	for _, ecNode := range allEcNodes {
@@ -136,12 +150,9 @@ func balanceEcVolumes(commandEnv *commandEnv, collection string, applyBalancing
 			possibleDestinationEcNodes = append(possibleDestinationEcNodes, ecNode)
 		}
 	}
-
 	// calculate average number of shards an ec node should have for one volume
 	averageShardsPerEcNode := int(math.Ceil(float64(erasure_coding.TotalShardsCount) / float64(len(possibleDestinationEcNodes))))
-
 	fmt.Printf("vid %d averageShardsPerEcNode %+v\n", vid, averageShardsPerEcNode)
-
 	// check whether this volume has ecNodes that are over average
 	isOverLimit := false
 	for _, ecNode := range locations {
@@ -152,17 +163,43 @@ func balanceEcVolumes(commandEnv *commandEnv, collection string, applyBalancing
 			break
 		}
 	}
-
 	if isOverLimit {
-
 		if err := spreadShardsIntoMoreDataNodes(ctx, commandEnv, averageShardsPerEcNode, collection, vid, locations, possibleDestinationEcNodes, applyBalancing); err != nil {
 			return err
 		}
-
 	}
+	return nil
+}
 
+func doDeduplicateEcShards(ctx context.Context, commandEnv *commandEnv, collection string, vid needle.VolumeId, locations []*EcNode, applyBalancing bool) error {
+
+	// check whether this volume has ecNodes that are over average
+	shardToLocations := make([][]*EcNode, erasure_coding.TotalShardsCount)
+	for _, ecNode := range locations {
+		shardBits := findEcVolumeShards(ecNode, vid)
+		for _, shardId := range shardBits.ShardIds() {
+			shardToLocations[shardId] = append(shardToLocations[shardId], ecNode)
+		}
+	}
+	for shardId, ecNodes := range shardToLocations {
+		if len(ecNodes) <= 1 {
+			continue
+		}
+		sortEcNodes(ecNodes)
+		fmt.Printf("ec shard %d.%d has %d copies, removing from %+v\n", vid, shardId, len(ecNodes), ecNodes[1:])
+		if !applyBalancing {
+			continue
+		}
+		for _, ecNode := range ecNodes[1:] {
+			duplicatedShardIds := []uint32{uint32(shardId)}
+			if err := unmountEcShards(ctx, commandEnv.option.GrpcDialOption, vid, ecNode.info.Id, duplicatedShardIds); err != nil {
+				return err
+			}
+			if err := sourceServerDeleteEcShards(ctx, commandEnv.option.GrpcDialOption, collection, vid, ecNode.info.Id, duplicatedShardIds); err != nil {
+				return err
+			}
+		}
 	}
-
 	return nil
 }