1 files changed, 211 insertions, 0 deletions
diff --git a/weed/shell/command_volume_balance.go b/weed/shell/command_volume_balance.go
new file mode 100644
index 000000000..26d77ab48
--- /dev/null
+++ b/weed/shell/command_volume_balance.go
@@ -0,0 +1,211 @@
+package shell
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"time"
+
+	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
+	"github.com/chrislusf/seaweedfs/weed/storage/needle"
+)
+
+func init() {
+	commands = append(commands, &commandVolumeBalance{})
+}
+
+type commandVolumeBalance struct {
+}
+
+func (c *commandVolumeBalance) Name() string {
+	return "volume.balance"
+}
+
+func (c *commandVolumeBalance) Help() string {
+	return `balance all volumes among volume servers
+
+	volume.balance [-c collectionName] [-f]
+
+	Algorithm:
+	For each type of volume server (different max volume count limit){
+		balanceWritableVolumes()
+		balanceReadOnlyVolumes()
+	}
+
+	func balanceWritableVolumes(){
+		idealWritableVolumes = totalWritableVolumes / numVolumeServers
+		for {
+			sort all volume servers ordered by{
+				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 balanceReadOnlyVolumes(){
+		//similar to balanceWritableVolumes
+	}
+
+`
+}
+
+func (c *commandVolumeBalance) Do(args []string, commandEnv *commandEnv, writer io.Writer) (err error) {
+
+	balanceCommand := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	collection := balanceCommand.String("c", "", "collection name. use \"ALL\" for all collections")
+	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)
+	for _, volumeServers := range typeToNodes {
+		if len(volumeServers) < 2 {
+			continue
+		}
+		balanceVolumeServers(commandEnv, volumeServers, resp.VolumeSizeLimitMb*1024*1024, *collection, *applyBalancing)
+	}
+	return nil
+}
+
+func balanceVolumeServers(commandEnv *commandEnv, dataNodeInfos []*master_pb.DataNodeInfo, volumeSizeLimit uint64, collection string, applyBalancing bool) {
+	var nodes []*Node
+	for _, dn := range dataNodeInfos {
+		nodes = append(nodes, &Node{
+			info: dn,
+		})
+	}
+
+	// balance writable volumes
+	for _, n := range nodes {
+		n.prepareVolumes(func(v *master_pb.VolumeInformationMessage) bool {
+			if collection != "ALL" {
+				if v.Collection != collection {
+					return false
+				}
+			}
+			return !v.ReadOnly && v.Size < volumeSizeLimit
+		})
+	}
+	balanceSelectedVolume(commandEnv, nodes, sortWritableVolumes, applyBalancing)
+
+	// balance readable volumes
+	for _, n := range nodes {
+		n.prepareVolumes(func(v *master_pb.VolumeInformationMessage) bool {
+			if collection != "ALL" {
+				if v.Collection != collection {
+					return false
+				}
+			}
+			return v.ReadOnly || v.Size >= volumeSizeLimit
+		})
+	}
+	balanceSelectedVolume(commandEnv, nodes, sortReadOnlyVolumes, applyBalancing)
+}
+
+func collectVolumeServersByType(t *master_pb.TopologyInfo) (typeToNodes map[uint64][]*master_pb.DataNodeInfo) {
+	typeToNodes = make(map[uint64][]*master_pb.DataNodeInfo)
+	for _, dc := range t.DataCenterInfos {
+		for _, r := range dc.RackInfos {
+			for _, dn := range r.DataNodeInfos {
+				typeToNodes[dn.MaxVolumeCount] = append(typeToNodes[dn.MaxVolumeCount], dn)
+			}
+		}
+	}
+	return
+}
+
+type Node struct {
+	info            *master_pb.DataNodeInfo
+	selectedVolumes map[uint32]*master_pb.VolumeInformationMessage
+}
+
+func sortWritableVolumes(volumes []*master_pb.VolumeInformationMessage) {
+	sort.Slice(volumes, func(i, j int) bool {
+		return volumes[i].Size < volumes[j].Size
+	})
+}
+
+func sortReadOnlyVolumes(volumes []*master_pb.VolumeInformationMessage) {
+	sort.Slice(volumes, func(i, j int) bool {
+		return volumes[i].Id < volumes[j].Id
+	})
+}
+
+func balanceSelectedVolume(commandEnv *commandEnv, nodes []*Node, sortCandidatesFn func(volumes []*master_pb.VolumeInformationMessage), applyBalancing bool) {
+	selectedVolumeCount := 0
+	for _, dn := range nodes {
+		selectedVolumeCount += len(dn.selectedVolumes)
+	}
+
+	idealSelectedVolumes := selectedVolumeCount / len(nodes)
+
+	hasMove := true
+
+	for hasMove {
+		hasMove = false
+		sort.Slice(nodes, func(i, j int) bool {
+			return len(nodes[i].selectedVolumes) < len(nodes[j].selectedVolumes)
+		})
+		emptyNode, fullNode := nodes[0], nodes[len(nodes)-1]
+		if len(fullNode.selectedVolumes) > idealSelectedVolumes && len(emptyNode.selectedVolumes)+1 <= idealSelectedVolumes {
+
+			// sort the volumes to move
+			var candidateVolumes []*master_pb.VolumeInformationMessage
+			for _, v := range fullNode.selectedVolumes {
+				candidateVolumes = append(candidateVolumes, v)
+			}
+			sortCandidatesFn(candidateVolumes)
+
+			for _, v := range candidateVolumes {
+				if _, found := emptyNode.selectedVolumes[v.Id]; !found {
+					moveVolume(commandEnv, v, fullNode, emptyNode, applyBalancing)
+					delete(fullNode.selectedVolumes, v.Id)
+					emptyNode.selectedVolumes[v.Id] = v
+					hasMove = true
+					break
+				}
+			}
+		}
+	}
+
+}
+
+func moveVolume(commandEnv *commandEnv, v *master_pb.VolumeInformationMessage, fullNode *Node, emptyNode *Node, applyBalancing bool) {
+	collectionPrefix := v.Collection + "_"
+	if v.Collection == "" {
+		collectionPrefix = ""
+	}
+	fmt.Fprintf(os.Stdout, "moving volume %s%d %s => %s\n", collectionPrefix, v.Id, fullNode.info.Id, emptyNode.info.Id)
+	if applyBalancing {
+		ctx := context.Background()
+		LiveMoveVolume(ctx, commandEnv.option.GrpcDialOption, needle.VolumeId(v.Id), fullNode.info.Id, emptyNode.info.Id, 5*time.Second)
+	}
+}
+
+func (node *Node) prepareVolumes(fn func(v *master_pb.VolumeInformationMessage) bool) {
+	node.selectedVolumes = make(map[uint32]*master_pb.VolumeInformationMessage)
+	for _, v := range node.info.VolumeInfos {
+		if fn(v) {
+			node.selectedVolumes[v.Id] = v
+		}
+	}
+}