1 files changed, 192 insertions, 0 deletions
diff --git a/weed/shell/command_volume_server_evacuate.go b/weed/shell/command_volume_server_evacuate.go
new file mode 100644
index 000000000..d27c66fa2
--- /dev/null
+++ b/weed/shell/command_volume_server_evacuate.go
@@ -0,0 +1,192 @@
+package shell
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
+	"github.com/chrislusf/seaweedfs/weed/storage/erasure_coding"
+	"github.com/chrislusf/seaweedfs/weed/storage/needle"
+	"io"
+	"sort"
+)
+
+func init() {
+	Commands = append(Commands, &commandVolumeServerEvacuate{})
+}
+
+type commandVolumeServerEvacuate struct {
+}
+
+func (c *commandVolumeServerEvacuate) Name() string {
+	return "volumeServer.evacuate"
+}
+
+func (c *commandVolumeServerEvacuate) Help() string {
+	return `move out all data on a volume server
+
+	volumeServer.evacuate -node <host:port>
+
+	This command moves all data away from the volume server.
+	The volumes on the volume servers will be redistributed.
+
+	Usually this is used to prepare to shutdown or upgrade the volume server.
+
+`
+}
+
+func (c *commandVolumeServerEvacuate) Do(args []string, commandEnv *CommandEnv, writer io.Writer) (err error) {
+
+	if err = commandEnv.confirmIsLocked(); err != nil {
+		return
+	}
+
+	vsEvacuateCommand := flag.NewFlagSet(c.Name(), flag.ContinueOnError)
+	volumeServer := vsEvacuateCommand.String("node", "", "<host>:<port> of the volume server")
+	applyChange := vsEvacuateCommand.Bool("force", false, "actually apply the changes")
+	if err = vsEvacuateCommand.Parse(args); err != nil {
+		return nil
+	}
+
+	if *volumeServer == "" {
+		return fmt.Errorf("need to specify volume server by -node=<host>:<port>")
+	}
+
+	return volumeServerEvacuate(commandEnv, *volumeServer, *applyChange, writer)
+
+}
+
+func volumeServerEvacuate(commandEnv *CommandEnv, volumeServer string, applyChange bool, writer io.Writer) (err error) {
+	// 1. confirm the volume server is part of the cluster
+	// 2. collect all other volume servers, sort by empty slots
+	// 3. move to any other volume server as long as it satisfy the replication requirements
+
+	// list all the volumes
+	var resp *master_pb.VolumeListResponse
+	err = commandEnv.MasterClient.WithClient(func(client master_pb.SeaweedClient) error {
+		resp, err = client.VolumeList(context.Background(), &master_pb.VolumeListRequest{})
+		return err
+	})
+	if err != nil {
+		return err
+	}
+
+	if err := evacuateNormalVolumes(commandEnv, resp, volumeServer, applyChange); err != nil {
+		return err
+	}
+
+	if err := evacuateEcVolumes(commandEnv, resp, volumeServer, applyChange); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func evacuateNormalVolumes(commandEnv *CommandEnv, resp *master_pb.VolumeListResponse, volumeServer string, applyChange bool) error {
+	// find this volume server
+	volumeServers := collectVolumeServersByDc(resp.TopologyInfo, "")
+	thisNode, otherNodes := nodesOtherThan(volumeServers, volumeServer)
+	if thisNode == nil {
+		return fmt.Errorf("%s is not found in this cluster", volumeServer)
+	}
+
+	// move away normal volumes
+	volumeReplicas, _ := collectVolumeReplicaLocations(resp)
+	for _, vol := range thisNode.info.VolumeInfos {
+		hasMoved, err := moveAwayOneNormalVolume(commandEnv, volumeReplicas, vol, thisNode, otherNodes, applyChange)
+		if err != nil {
+			return fmt.Errorf("move away volume %d from %s: %v", vol.Id, volumeServer, err)
+		}
+		if !hasMoved {
+			return fmt.Errorf("failed to move volume %d from %s", vol.Id, volumeServer)
+		}
+	}
+	return nil
+}
+
+func evacuateEcVolumes(commandEnv *CommandEnv, resp *master_pb.VolumeListResponse, volumeServer string, applyChange bool) error {
+	// find this ec volume server
+	ecNodes, _ := collectEcVolumeServersByDc(resp.TopologyInfo, "")
+	thisNode, otherNodes := ecNodesOtherThan(ecNodes, volumeServer)
+	if thisNode == nil {
+		return fmt.Errorf("%s is not found in this cluster", volumeServer)
+	}
+
+	// move away ec volumes
+	for _, ecShardInfo := range thisNode.info.EcShardInfos {
+		hasMoved, err := moveAwayOneEcVolume(commandEnv, ecShardInfo, thisNode, otherNodes, applyChange)
+		if err != nil {
+			return fmt.Errorf("move away volume %d from %s: %v", ecShardInfo.Id, volumeServer, err)
+		}
+		if !hasMoved {
+			return fmt.Errorf("failed to move ec volume %d from %s", ecShardInfo.Id, volumeServer)
+		}
+	}
+	return nil
+}
+
+func moveAwayOneEcVolume(commandEnv *CommandEnv, ecShardInfo *master_pb.VolumeEcShardInformationMessage, thisNode *EcNode, otherNodes []*EcNode, applyChange bool) (hasMoved bool, err error) {
+
+	for _, shardId := range erasure_coding.ShardBits(ecShardInfo.EcIndexBits).ShardIds() {
+
+		sort.Slice(otherNodes, func(i, j int) bool {
+			return otherNodes[i].localShardIdCount(ecShardInfo.Id) < otherNodes[j].localShardIdCount(ecShardInfo.Id)
+		})
+
+		for i := 0; i < len(otherNodes); i++ {
+			emptyNode := otherNodes[i]
+			err = moveMountedShardToEcNode(commandEnv, thisNode, ecShardInfo.Collection, needle.VolumeId(ecShardInfo.Id), shardId, emptyNode, applyChange)
+			if err != nil {
+				return
+			} else {
+				hasMoved = true
+				break
+			}
+		}
+		if !hasMoved {
+			return
+		}
+	}
+
+	return
+}
+
+func moveAwayOneNormalVolume(commandEnv *CommandEnv, volumeReplicas map[uint32][]*VolumeReplica, vol *master_pb.VolumeInformationMessage, thisNode *Node, otherNodes []*Node, applyChange bool) (hasMoved bool, err error) {
+	sort.Slice(otherNodes, func(i, j int) bool {
+		return otherNodes[i].localVolumeRatio() < otherNodes[j].localVolumeRatio()
+	})
+
+	for i := 0; i < len(otherNodes); i++ {
+		emptyNode := otherNodes[i]
+		hasMoved, err = maybeMoveOneVolume(commandEnv, volumeReplicas, thisNode, vol, emptyNode, applyChange)
+		if err != nil {
+			return
+		}
+		if hasMoved {
+			break
+		}
+	}
+	return
+}
+
+func nodesOtherThan(volumeServers []*Node, thisServer string) (thisNode *Node, otherNodes []*Node) {
+	for _, node := range volumeServers {
+		if node.info.Id == thisServer {
+			thisNode = node
+			continue
+		}
+		otherNodes = append(otherNodes, node)
+	}
+	return
+}
+
+func ecNodesOtherThan(volumeServers []*EcNode, thisServer string) (thisNode *EcNode, otherNodes []*EcNode) {
+	for _, node := range volumeServers {
+		if node.info.Id == thisServer {
+			thisNode = node
+			continue
+		}
+		otherNodes = append(otherNodes, node)
+	}
+	return
+}