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package shell
import ( "flag" "fmt" "github.com/seaweedfs/seaweedfs/weed/pb" "github.com/seaweedfs/seaweedfs/weed/storage/erasure_coding" "github.com/seaweedfs/seaweedfs/weed/storage/needle" "github.com/seaweedfs/seaweedfs/weed/storage/types" "golang.org/x/exp/slices" "io" )
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|<collection_name>] [-force] [-dataCenter <data_center>]
Algorithm:
func EcBalance() { 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) {
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 } infoAboutSimulationMode(writer, *applyBalancing, "-force")
if err = commandEnv.confirmIsLocked(args); err != nil { return }
// 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 within 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, pb.NewServerAddressFromDataNode(ecNode.info), duplicatedShardIds); err != nil { return err } if err := sourceServerDeleteEcShards(commandEnv.option.GrpcDialOption, collection, vid, pb.NewServerAddressFromDataNode(ecNode.info), 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 { if _, found := n.info.DiskInfos[string(types.HardDriveType)]; found { 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(ecNode *EcNode) (id string, count int) { diskInfo, found := ecNode.info.DiskInfos[string(types.HardDriveType)] if !found { return } for _, ecShardInfo := range diskInfo.EcShardInfos { count += erasure_coding.ShardBits(ecShardInfo.EcIndexBits).ShardIdCount() } return ecNode.info.Id, count })
var totalShardCount int for _, count := range ecNodeIdToShardCount { totalShardCount += count }
averageShardCount := ceilDivide(totalShardCount, len(rackEcNodes))
hasMove := true for hasMove { hasMove = false slices.SortFunc(rackEcNodes, func(a, b *EcNode) int { return b.freeEcSlot - a.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) if emptyDiskInfo, found := emptyNode.info.DiskInfos[string(types.HardDriveType)]; found { for _, shards := range emptyDiskInfo.EcShardInfos { emptyNodeIds[shards.Id] = true } } if fullDiskInfo, found := fullNode.info.DiskInfos[string(types.HardDriveType)]; found { for _, shards := range fullDiskInfo.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 {
sortEcNodesByFreeslotsDescending(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(), }) } } slices.SortFunc(candidateEcNodes, func(a, b *CandidateEcNode) int { return b.shardCount - a.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 { diskInfo, found := ecNode.info.DiskInfos[string(types.HardDriveType)] if !found { continue } for _, shardInfo := range diskInfo.EcShardInfos { vidLocations[needle.VolumeId(shardInfo.Id)] = append(vidLocations[needle.VolumeId(shardInfo.Id)], ecNode) } } return vidLocations }
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