package shell import ( "flag" "fmt" "io" "sort" "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 all racks and volume servers ec.balance [-c EACH_COLLECTION|] [-force] [-dataCenter ] Algorithm: For each type of volume server (different max volume count limit){ for each collection: balanceEcVolumes(collectionName) for each rack: balanceEcRack(rack) } func balanceEcVolumes(collectionName){ for each volume: doDeduplicateEcShards(volumeId) tracks rack~shardCount mapping for each volume: doBalanceEcShardsAcrossRacks(volumeId) for each volume: doBalanceEcShardsWithinRacks(volumeId) } // spread ec shards into more racks func doBalanceEcShardsAcrossRacks(volumeId){ tracks rack~volumeIdShardCount mapping averageShardsPerEcRack = totalShardNumber / numRacks // totalShardNumber is 14 for now, later could varies for each dc ecShardsToMove = select overflown ec shards from racks with ec shard counts > averageShardsPerEcRack for each ecShardsToMove { destRack = pickOneRack(rack~shardCount, rack~volumeIdShardCount, averageShardsPerEcRack) destVolumeServers = volume servers on the destRack pickOneEcNodeAndMoveOneShard(destVolumeServers) } } func doBalanceEcShardsWithinRacks(volumeId){ racks = collect all racks that the volume id is on for rack, shards := range racks doBalanceEcShardsWithinOneRack(volumeId, shards, rack) } // move ec shards func doBalanceEcShardsWithinOneRack(volumeId, shards, rackId){ tracks volumeServer~volumeIdShardCount mapping averageShardCount = len(shards) / numVolumeServers volumeServersOverAverage = volume servers with volumeId's ec shard counts > averageShardsPerEcRack ecShardsToMove = select overflown ec shards from volumeServersOverAverage for each ecShardsToMove { destVolumeServer = pickOneVolumeServer(volumeServer~shardCount, volumeServer~volumeIdShardCount, averageShardCount) pickOneEcNodeAndMoveOneShard(destVolumeServers) } } // move ec shards while keeping shard distribution for the same volume unchanged or more even func balanceEcRack(rack){ averageShardCount = total shards / numVolumeServers for hasMovedOneEcShard { sort all volume servers ordered by the number of local ec shards pick the volume server A with the lowest number of ec shards x pick the volume server B with the highest number of ec shards y if y > averageShardCount and x +1 <= averageShardCount { if B has a ec shard with volume id v that A does not have { move one ec shard v from B to A hasMovedOneEcShard = true } } } } ` } func (c *commandEcBalance) Do(args []string, commandEnv *CommandEnv, writer io.Writer) (err error) { if err = commandEnv.confirmIsLocked(); err != nil { return } balanceCommand := flag.NewFlagSet(c.Name(), flag.ContinueOnError) collection := balanceCommand.String("collection", "EACH_COLLECTION", "collection name, or \"EACH_COLLECTION\" for each collection") dc := balanceCommand.String("dataCenter", "", "only apply the balancing for this dataCenter") applyBalancing := balanceCommand.Bool("force", false, "apply the balancing plan") if err = balanceCommand.Parse(args); err != nil { return nil } // collect all ec nodes allEcNodes, totalFreeEcSlots, err := collectEcNodes(commandEnv, *dc) if err != nil { return err } if totalFreeEcSlots < 1 { return fmt.Errorf("no free ec shard slots. only %d left", totalFreeEcSlots) } racks := collectRacks(allEcNodes) if *collection == "EACH_COLLECTION" { collections, err := ListCollectionNames(commandEnv, false, true) 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, allEcNodes, racks, *applyBalancing); err != nil { return err } } } else { if err = balanceEcVolumes(commandEnv, *collection, allEcNodes, racks, *applyBalancing); err != nil { return err } } if err := balanceEcRacks(commandEnv, racks, *applyBalancing); err != nil { return fmt.Errorf("balance ec racks: %v", err) } return nil } func collectRacks(allEcNodes []*EcNode) map[RackId]*EcRack { // collect racks info racks := make(map[RackId]*EcRack) for _, ecNode := range allEcNodes { if racks[ecNode.rack] == nil { racks[ecNode.rack] = &EcRack{ ecNodes: make(map[EcNodeId]*EcNode), } } racks[ecNode.rack].ecNodes[EcNodeId(ecNode.info.Id)] = ecNode racks[ecNode.rack].freeEcSlot += ecNode.freeEcSlot } return racks } func balanceEcVolumes(commandEnv *CommandEnv, collection string, allEcNodes []*EcNode, racks map[RackId]*EcRack, applyBalancing bool) error { fmt.Printf("balanceEcVolumes %s\n", collection) if err := deleteDuplicatedEcShards(commandEnv, allEcNodes, collection, applyBalancing); err != nil { return fmt.Errorf("delete duplicated collection %s ec shards: %v", collection, err) } if err := balanceEcShardsAcrossRacks(commandEnv, allEcNodes, racks, collection, applyBalancing); err != nil { return fmt.Errorf("balance across racks collection %s ec shards: %v", collection, err) } if err := balanceEcShardsWithinRacks(commandEnv, allEcNodes, racks, collection, applyBalancing); err != nil { return fmt.Errorf("balance across racks collection %s ec shards: %v", collection, err) } return nil } func deleteDuplicatedEcShards(commandEnv *CommandEnv, allEcNodes []*EcNode, collection string, applyBalancing bool) error { // vid => []ecNode vidLocations := collectVolumeIdToEcNodes(allEcNodes) // deduplicate ec shards for vid, locations := range vidLocations { if err := doDeduplicateEcShards(commandEnv, collection, vid, locations, applyBalancing); err != nil { return err } } return nil } func doDeduplicateEcShards(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 } sortEcNodesByFreeslotsAscending(ecNodes) fmt.Printf("ec shard %d.%d has %d copies, keeping %v\n", vid, shardId, len(ecNodes), ecNodes[0].info.Id) if !applyBalancing { continue } duplicatedShardIds := []uint32{uint32(shardId)} for _, ecNode := range ecNodes[1:] { if err := unmountEcShards(commandEnv.option.GrpcDialOption, vid, ecNode.info.Id, duplicatedShardIds); err != nil { return err } if err := sourceServerDeleteEcShards(commandEnv.option.GrpcDialOption, collection, vid, ecNode.info.Id, duplicatedShardIds); err != nil { return err } ecNode.deleteEcVolumeShards(vid, duplicatedShardIds) } } return nil } func balanceEcShardsAcrossRacks(commandEnv *CommandEnv, allEcNodes []*EcNode, racks map[RackId]*EcRack, collection string, applyBalancing bool) error { // collect vid => []ecNode, since previous steps can change the locations vidLocations := collectVolumeIdToEcNodes(allEcNodes) // spread the ec shards evenly for vid, locations := range vidLocations { if err := doBalanceEcShardsAcrossRacks(commandEnv, collection, vid, locations, racks, applyBalancing); err != nil { return err } } return nil } func doBalanceEcShardsAcrossRacks(commandEnv *CommandEnv, collection string, vid needle.VolumeId, locations []*EcNode, racks map[RackId]*EcRack, applyBalancing bool) error { // calculate average number of shards an ec rack should have for one volume averageShardsPerEcRack := ceilDivide(erasure_coding.TotalShardsCount, len(racks)) // see the volume's shards are in how many racks, and how many in each rack rackToShardCount := groupByCount(locations, func(ecNode *EcNode) (id string, count int) { shardBits := findEcVolumeShards(ecNode, vid) return string(ecNode.rack), shardBits.ShardIdCount() }) rackEcNodesWithVid := groupBy(locations, func(ecNode *EcNode) string { return string(ecNode.rack) }) // ecShardsToMove = select overflown ec shards from racks with ec shard counts > averageShardsPerEcRack ecShardsToMove := make(map[erasure_coding.ShardId]*EcNode) for rackId, count := range rackToShardCount { if count > averageShardsPerEcRack { possibleEcNodes := rackEcNodesWithVid[rackId] for shardId, ecNode := range pickNEcShardsToMoveFrom(possibleEcNodes, vid, count-averageShardsPerEcRack) { ecShardsToMove[shardId] = ecNode } } } for shardId, ecNode := range ecShardsToMove { rackId := pickOneRack(racks, rackToShardCount, averageShardsPerEcRack) if rackId == "" { fmt.Printf("ec shard %d.%d at %s can not find a destination rack\n", vid, shardId, ecNode.info.Id) continue } var possibleDestinationEcNodes []*EcNode for _, n := range racks[rackId].ecNodes { possibleDestinationEcNodes = append(possibleDestinationEcNodes, n) } err := pickOneEcNodeAndMoveOneShard(commandEnv, averageShardsPerEcRack, ecNode, collection, vid, shardId, possibleDestinationEcNodes, applyBalancing) if err != nil { return err } rackToShardCount[string(rackId)] += 1 rackToShardCount[string(ecNode.rack)] -= 1 racks[rackId].freeEcSlot -= 1 racks[ecNode.rack].freeEcSlot += 1 } return nil } func pickOneRack(rackToEcNodes map[RackId]*EcRack, rackToShardCount map[string]int, averageShardsPerEcRack int) RackId { // TODO later may need to add some randomness for rackId, rack := range rackToEcNodes { if rackToShardCount[string(rackId)] >= averageShardsPerEcRack { continue } if rack.freeEcSlot <= 0 { continue } return rackId } return "" } func balanceEcShardsWithinRacks(commandEnv *CommandEnv, allEcNodes []*EcNode, racks map[RackId]*EcRack, collection string, applyBalancing bool) error { // collect vid => []ecNode, since previous steps can change the locations vidLocations := collectVolumeIdToEcNodes(allEcNodes) // spread the ec shards evenly for vid, locations := range vidLocations { // see the volume's shards are in how many racks, and how many in each rack rackToShardCount := groupByCount(locations, func(ecNode *EcNode) (id string, count int) { shardBits := findEcVolumeShards(ecNode, vid) return string(ecNode.rack), shardBits.ShardIdCount() }) rackEcNodesWithVid := groupBy(locations, func(ecNode *EcNode) string { return string(ecNode.rack) }) for rackId, _ := range rackToShardCount { var possibleDestinationEcNodes []*EcNode for _, n := range racks[RackId(rackId)].ecNodes { possibleDestinationEcNodes = append(possibleDestinationEcNodes, n) } sourceEcNodes := rackEcNodesWithVid[rackId] averageShardsPerEcNode := ceilDivide(rackToShardCount[rackId], len(possibleDestinationEcNodes)) if err := doBalanceEcShardsWithinOneRack(commandEnv, averageShardsPerEcNode, collection, vid, sourceEcNodes, possibleDestinationEcNodes, applyBalancing); err != nil { return err } } } return nil } func doBalanceEcShardsWithinOneRack(commandEnv *CommandEnv, averageShardsPerEcNode int, collection string, 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(commandEnv, averageShardsPerEcNode, ecNode, collection, vid, shardId, possibleDestinationEcNodes, applyBalancing) if err != nil { return err } overLimitCount-- } } return nil } func balanceEcRacks(commandEnv *CommandEnv, racks map[RackId]*EcRack, applyBalancing bool) error { // balance one rack for all ec shards for _, ecRack := range racks { if err := doBalanceEcRack(commandEnv, ecRack, applyBalancing); err != nil { return err } } return nil } func doBalanceEcRack(commandEnv *CommandEnv, ecRack *EcRack, applyBalancing bool) error { if len(ecRack.ecNodes) <= 1 { return nil } var rackEcNodes []*EcNode for _, node := range ecRack.ecNodes { rackEcNodes = append(rackEcNodes, node) } ecNodeIdToShardCount := groupByCount(rackEcNodes, func(node *EcNode) (id string, count int) { for _, ecShardInfo := range node.info.EcShardInfos { count += erasure_coding.ShardBits(ecShardInfo.EcIndexBits).ShardIdCount() } return node.info.Id, count }) var totalShardCount int for _, count := range ecNodeIdToShardCount { totalShardCount += count } averageShardCount := ceilDivide(totalShardCount, len(rackEcNodes)) hasMove := true for hasMove { hasMove = false sort.Slice(rackEcNodes, func(i, j int) bool { return rackEcNodes[i].freeEcSlot > rackEcNodes[j].freeEcSlot }) emptyNode, fullNode := rackEcNodes[0], rackEcNodes[len(rackEcNodes)-1] emptyNodeShardCount, fullNodeShardCount := ecNodeIdToShardCount[emptyNode.info.Id], ecNodeIdToShardCount[fullNode.info.Id] if fullNodeShardCount > averageShardCount && emptyNodeShardCount+1 <= averageShardCount { emptyNodeIds := make(map[uint32]bool) for _, shards := range emptyNode.info.EcShardInfos { emptyNodeIds[shards.Id] = true } for _, shards := range fullNode.info.EcShardInfos { if _, found := emptyNodeIds[shards.Id]; !found { for _, shardId := range erasure_coding.ShardBits(shards.EcIndexBits).ShardIds() { fmt.Printf("%s moves ec shards %d.%d to %s\n", fullNode.info.Id, shards.Id, shardId, emptyNode.info.Id) err := moveMountedShardToEcNode(commandEnv, fullNode, shards.Collection, needle.VolumeId(shards.Id), shardId, emptyNode, applyBalancing) if err != nil { return err } ecNodeIdToShardCount[emptyNode.info.Id]++ ecNodeIdToShardCount[fullNode.info.Id]-- hasMove = true break } break } } } } return nil } func pickOneEcNodeAndMoveOneShard(commandEnv *CommandEnv, averageShardsPerEcNode int, existingLocation *EcNode, collection string, vid needle.VolumeId, shardId erasure_coding.ShardId, possibleDestinationEcNodes []*EcNode, applyBalancing bool) error { sortEcNodesByFreeslotsDecending(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 := moveMountedShardToEcNode(commandEnv, existingLocation, collection, vid, shardId, destEcNode, applyBalancing) if err != nil { return err } return nil } return nil } func pickNEcShardsToMoveFrom(ecNodes []*EcNode, vid needle.VolumeId, n int) map[erasure_coding.ShardId]*EcNode { picked := make(map[erasure_coding.ShardId]*EcNode) var candidateEcNodes []*CandidateEcNode for _, ecNode := range ecNodes { shardBits := findEcVolumeShards(ecNode, vid) if shardBits.ShardIdCount() > 0 { candidateEcNodes = append(candidateEcNodes, &CandidateEcNode{ ecNode: ecNode, shardCount: shardBits.ShardIdCount(), }) } } sort.Slice(candidateEcNodes, func(i, j int) bool { return candidateEcNodes[i].shardCount > candidateEcNodes[j].shardCount }) for i := 0; i < n; i++ { selectedEcNodeIndex := -1 for i, candidateEcNode := range candidateEcNodes { shardBits := findEcVolumeShards(candidateEcNode.ecNode, vid) if shardBits > 0 { selectedEcNodeIndex = i for _, shardId := range shardBits.ShardIds() { candidateEcNode.shardCount-- picked[shardId] = candidateEcNode.ecNode candidateEcNode.ecNode.deleteEcVolumeShards(vid, []uint32{uint32(shardId)}) break } break } } if selectedEcNodeIndex >= 0 { ensureSortedEcNodes(candidateEcNodes, selectedEcNodeIndex, func(i, j int) bool { return candidateEcNodes[i].shardCount > candidateEcNodes[j].shardCount }) } } return picked } func collectVolumeIdToEcNodes(allEcNodes []*EcNode) map[needle.VolumeId][]*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) } } return vidLocations }