print out the ec balancing plan

weed/shell/command_ec_balance.go

@@ -0,0 +1,245 @@
+package shell
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"math"
+
+	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
+	"github.com/chrislusf/seaweedfs/weed/storage/erasure_coding"
+	"github.com/chrislusf/seaweedfs/weed/storage/needle"
+)
+
+func init() {
+	commands = append(commands, &commandEcBalance{})
+}
+
+type commandEcBalance struct {
+}
+
+func (c *commandEcBalance) Name() string {
+	return "ec.balance"
+}
+
+func (c *commandEcBalance) Help() string {
+	return `balance all ec shards among volume servers
+
+	ec.balance [-c ALL|EACH_COLLECTION|<collection_name>] [-f]
+
+	Algorithm:
+
+	For each type of volume server (different max volume count limit){
+		for each collection {
+			balanceEcVolumes()
+		}
+	}
+
+	func balanceEcVolumes(){
+		idealWritableVolumes = totalWritableVolumes / numVolumeServers
+		for {
+			sort all volume servers ordered by the number of local writable volumes
+			pick the volume server A with the lowest number of writable volumes x
+			pick the volume server B with the highest number of writable volumes y
+			if y > idealWritableVolumes and x +1 <= idealWritableVolumes {
+				if B has a writable volume id v that A does not have {
+					move writable volume v from A to B
+				}
+			}
+		}
+	}
+
+`
+}
+
+func (c *commandEcBalance) Do(args []string, commandEnv *commandEnv, writer io.Writer) (err error) {
+
+	balanceCommand := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	collection := balanceCommand.String("c", "EACH_COLLECTION", "collection name, or use \"ALL_COLLECTIONS\" across collections, \"EACH_COLLECTION\" for each collection")
+	dc := balanceCommand.String("dataCenter", "", "only apply the balancing for this dataCenter")
+	applyBalancing := balanceCommand.Bool("f", false, "apply the balancing plan.")
+	if err = balanceCommand.Parse(args); err != nil {
+		return nil
+	}
+
+	var resp *master_pb.VolumeListResponse
+	ctx := context.Background()
+	err = commandEnv.masterClient.WithClient(ctx, func(client master_pb.SeaweedClient) error {
+		resp, err = client.VolumeList(ctx, &master_pb.VolumeListRequest{})
+		return err
+	})
+	if err != nil {
+		return err
+	}
+
+	typeToNodes := collectVolumeServersByType(resp.TopologyInfo, *dc)
+	for _, volumeServers := range typeToNodes {
+
+		fmt.Printf("balanceEcVolumes servers %d\n", len(volumeServers))
+
+		if len(volumeServers) < 2 {
+			continue
+		}
+
+		if *collection == "EACH_COLLECTION" {
+			collections, err := ListCollectionNames(commandEnv)
+			if err != nil {
+				return err
+			}
+			fmt.Printf("balanceEcVolumes collections %+v\n", len(collections))
+			for _, c := range collections {
+				fmt.Printf("balanceEcVolumes collection %+v\n", c)
+				if err = balanceEcVolumes(commandEnv, c, *applyBalancing); err != nil {
+					return err
+				}
+			}
+		} else if *collection == "ALL" {
+			if err = balanceEcVolumes(commandEnv, "ALL", *applyBalancing); err != nil {
+				return err
+			}
+		} else {
+			if err = balanceEcVolumes(commandEnv, *collection, *applyBalancing); err != nil {
+				return err
+			}
+		}
+
+	}
+	return nil
+}
+
+func balanceEcVolumes(commandEnv *commandEnv, collection string, applyBalancing bool) error {
+
+	ctx := context.Background()
+
+	fmt.Printf("balanceEcVolumes %s\n", collection)
+
+	// collect all ec nodes
+	allEcNodes, totalFreeEcSlots, err := collectEcNodes(ctx, commandEnv)
+	if err != nil {
+		return err
+	}
+	if totalFreeEcSlots < 1 {
+		return fmt.Errorf("no free ec shard slots. only %d left", totalFreeEcSlots)
+	}
+
+	// vid => []ecNode
+	vidLocations := make(map[needle.VolumeId][]*EcNode)
+	for _, ecNode := range allEcNodes {
+		for _, shardInfo := range ecNode.info.EcShardInfos {
+			vidLocations[needle.VolumeId(shardInfo.Id)] = append(vidLocations[needle.VolumeId(shardInfo.Id)], ecNode)
+		}
+	}
+
+	for vid, locations := range vidLocations {
+
+		// collect all ec nodes with at least one free slot
+		var possibleDestinationEcNodes []*EcNode
+		for _, ecNode := range allEcNodes {
+			if ecNode.freeEcSlot > 0 {
+				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 {
+			shardBits := findEcVolumeShards(ecNode, vid)
+			if shardBits.ShardIdCount() > averageShardsPerEcNode {
+				isOverLimit = true
+				fmt.Printf("vid %d %s has %d shards, isOverLimit %+v\n", vid, ecNode.info.Id, shardBits.ShardIdCount(), isOverLimit)
+				break
+			}
+		}
+
+		if isOverLimit {
+
+			if err := spreadShardsIntoMoreDataNodes(ctx, commandEnv, averageShardsPerEcNode, vid, locations, possibleDestinationEcNodes, applyBalancing); err != nil {
+				return err
+			}
+
+		}
+
+	}
+
+	return nil
+}
+
+func spreadShardsIntoMoreDataNodes(ctx context.Context, commandEnv *commandEnv, averageShardsPerEcNode int, vid needle.VolumeId, existingLocations, possibleDestinationEcNodes []*EcNode, applyBalancing bool) error {
+
+	for _, ecNode := range existingLocations {
+
+		shardBits := findEcVolumeShards(ecNode, vid)
+		overLimitCount := shardBits.ShardIdCount() - averageShardsPerEcNode
+
+		for _, shardId := range shardBits.ShardIds() {
+
+			if overLimitCount <= 0 {
+				break
+			}
+
+			fmt.Printf("%s has %d overlimit, moving ec shard %d.%d\n", ecNode.info.Id, overLimitCount, vid, shardId)
+
+			err := pickOneEcNodeAndMoveOneShard(ctx, commandEnv, averageShardsPerEcNode, ecNode, vid, shardId, possibleDestinationEcNodes, applyBalancing)
+			if err != nil {
+				return err
+			}
+
+			overLimitCount--
+		}
+	}
+
+	return nil
+}
+
+func pickOneEcNodeAndMoveOneShard(ctx context.Context, commandEnv *commandEnv, averageShardsPerEcNode int, existingLocation *EcNode, vid needle.VolumeId, shardId erasure_coding.ShardId, possibleDestinationEcNodes []*EcNode, applyBalancing bool) error {
+
+	sortEcNodes(possibleDestinationEcNodes)
+
+	for _, destEcNode := range possibleDestinationEcNodes {
+		if destEcNode.info.Id == existingLocation.info.Id {
+			continue
+		}
+
+		if destEcNode.freeEcSlot <= 0 {
+			continue
+		}
+		if findEcVolumeShards(destEcNode, vid).ShardIdCount() >= averageShardsPerEcNode {
+			continue
+		}
+
+		fmt.Printf("%s moves ec shard %d.%d to %s\n", existingLocation.info.Id, vid, shardId, destEcNode.info.Id)
+
+		err := moveOneShardToEcNode(ctx, commandEnv, existingLocation, vid, shardId, destEcNode, applyBalancing)
+		if err != nil {
+			return err
+		}
+
+		destEcNode.freeEcSlot--
+		return nil
+	}
+
+	return nil
+}
+
+func moveOneShardToEcNode(ctx context.Context, commandEnv *commandEnv, existingLocation *EcNode, vid needle.VolumeId, shardId erasure_coding.ShardId, destinationEcNode *EcNode, applyBalancing bool) error {
+
+	fmt.Printf("moved ec shard %d.%d %s => %s\n", vid, shardId, existingLocation.info.Id, destinationEcNode.info.Id)
+	return nil
+}
+
+func findEcVolumeShards(ecNode *EcNode, vid needle.VolumeId) erasure_coding.ShardBits {
+
+	for _, shardInfo := range ecNode.info.EcShardInfos {
+		if needle.VolumeId(shardInfo.Id) == vid {
+			return erasure_coding.ShardBits(shardInfo.EcIndexBits)
+		}
+	}
+
+	return 0
+}