diff --git a/go/storage/disk_location.go b/go/storage/disk_location.go
index 9267343e4..b34535c7a 100644
--- a/go/storage/disk_location.go
+++ b/go/storage/disk_location.go
@@ -48,7 +48,7 @@ func (l *DiskLocation) LoadExistingVolumes(needleMapKind NeedleMapType) {
 			}
 		}
 	}
-	glog.V(0).Infoln("Store started on dir:", l.Directory, "with", len(l.volumes), "volumes", "max", l.MaxVolumeCount)
+	glog.V(0).Infoln("Store started on dir:", l.Directory, "with", len(l.VolumeCount()), "volumes", "max", l.MaxVolumeCount)
 }
 
 func (l *DiskLocation) AddVolume(vid VolumeId, v *Volume) {
diff --git a/go/storage/store_task.go b/go/storage/store_task.go
index 25e6f1fb4..5d9efbadf 100644
--- a/go/storage/store_task.go
+++ b/go/storage/store_task.go
@@ -5,6 +5,8 @@ import (
 	"net/url"
 	"time"
 
+	"sync"
+
 	"github.com/chrislusf/seaweedfs/go/glog"
 )
 
@@ -28,7 +30,7 @@ type TaskWorker interface {
 	Info() url.Values
 }
 
-type Task struct {
+type task struct {
 	Id              string
 	startTime       time.Time
 	worker          TaskWorker
@@ -38,18 +40,19 @@ type Task struct {
 }
 
 type TaskManager struct {
-	TaskList map[string]*Task
+	taskList map[string]*task
+	lock     sync.RWMutex
 }
 
-func NewTask(worker TaskWorker, id string) *Task {
-	t := &Task{
+func newTask(worker TaskWorker, id string) *task {
+	t := &task{
 		Id:        id,
 		worker:    worker,
 		startTime: time.Now(),
 		result:    ErrTaskNotFinish,
 		ch:        make(chan bool, 1),
 	}
-	go func(t *Task) {
+	go func(t *task) {
 		t.result = t.worker.Run()
 		if t.cleanWhenFinish {
 			glog.V(0).Infof("clean task (%s) when finish.", t.Id)
@@ -61,7 +64,7 @@ func NewTask(worker TaskWorker, id string) *Task {
 	return t
 }
 
-func (t *Task) QueryResult(waitDuration time.Duration) error {
+func (t *task) queryResult(waitDuration time.Duration) error {
 	if t.result == ErrTaskNotFinish && waitDuration > 0 {
 		select {
 		case <-time.After(waitDuration):
@@ -73,15 +76,17 @@ func (t *Task) QueryResult(waitDuration time.Duration) error {
 
 func NewTaskManager() *TaskManager {
 	return &TaskManager{
-		TaskList: make(map[string]*Task),
+		taskList: make(map[string]*task),
 	}
 }
 
 func (tm *TaskManager) NewTask(s *Store, args url.Values) (tid string, e error) {
+	tm.lock.Lock()
+	defer tm.lock.Unlock()
 	tt := args.Get("task")
 	vid := args.Get("volume")
 	tid = tt + "-" + vid
-	if _, ok := tm.TaskList[tid]; ok {
+	if _, ok := tm.taskList[tid]; ok {
 		return tid, ErrTaskExists
 	}
 
@@ -99,37 +104,43 @@ func (tm *TaskManager) NewTask(s *Store, args url.Values) (tid string, e error)
 	if tw == nil {
 		return "", ErrTaskInvalid
 	}
-	tm.TaskList[tid] = NewTask(tw, tid)
+	tm.taskList[tid] = newTask(tw, tid)
 	return tid, nil
 }
 
 func (tm *TaskManager) QueryResult(tid string, waitDuration time.Duration) (e error) {
-	t, ok := tm.TaskList[tid]
+	tm.lock.RLock()
+	defer tm.lock.RUnlock()
+	t, ok := tm.taskList[tid]
 	if !ok {
 		return ErrTaskNotFound
 	}
-	return t.QueryResult(waitDuration)
+	return t.queryResult(waitDuration)
 }
 
 func (tm *TaskManager) Commit(tid string) (e error) {
-	t, ok := tm.TaskList[tid]
+	tm.lock.Lock()
+	defer tm.lock.Unlock()
+	t, ok := tm.taskList[tid]
 	if !ok {
 		return ErrTaskNotFound
 	}
-	if t.QueryResult(time.Second*30) == ErrTaskNotFinish {
+	if t.queryResult(time.Second*30) == ErrTaskNotFinish {
 		return ErrTaskNotFinish
 	}
-	delete(tm.TaskList, tid)
+	delete(tm.taskList, tid)
 	return t.worker.Commit()
 }
 
 func (tm *TaskManager) Clean(tid string) error {
-	t, ok := tm.TaskList[tid]
+	tm.lock.Lock()
+	defer tm.lock.Unlock()
+	t, ok := tm.taskList[tid]
 	if !ok {
 		return ErrTaskNotFound
 	}
-	delete(tm.TaskList, tid)
-	if t.QueryResult(time.Second*30) == ErrTaskNotFinish {
+	delete(tm.taskList, tid)
+	if t.queryResult(time.Second*30) == ErrTaskNotFinish {
 		t.cleanWhenFinish = true
 		glog.V(0).Infof("task (%s) is not finish, clean it later.", tid)
 	} else {
@@ -139,7 +150,9 @@ func (tm *TaskManager) Clean(tid string) error {
 }
 
 func (tm *TaskManager) ElapsedDuration(tid string) (time.Duration, error) {
-	t, ok := tm.TaskList[tid]
+	tm.lock.RLock()
+	defer tm.lock.RUnlock()
+	t, ok := tm.taskList[tid]
 	if !ok {
 		return 0, ErrTaskNotFound
 	}