diff --git a/weed/storage/disk_location.go b/weed/storage/disk_location.go
index a81ae23ba..6f938da8f 100644
--- a/weed/storage/disk_location.go
+++ b/weed/storage/disk_location.go
@@ -24,8 +24,8 @@ type DiskLocation struct {
 	DirectoryUuid          string
 	IdxDirectory           string
 	DiskType               types.DiskType
-	MaxVolumeCount         int
-	OriginalMaxVolumeCount int
+	MaxVolumeCount         int32
+	OriginalMaxVolumeCount int32
 	MinFreeSpace           util.MinFreeSpace
 	volumes                map[needle.VolumeId]*Volume
 	volumesLock            sync.RWMutex
@@ -58,7 +58,7 @@ func GenerateDirUuid(dir string) (dirUuidString string, err error) {
 	return dirUuidString, nil
 }
 
-func NewDiskLocation(dir string, maxVolumeCount int, minFreeSpace util.MinFreeSpace, idxDir string, diskType types.DiskType) *DiskLocation {
+func NewDiskLocation(dir string, maxVolumeCount int32, minFreeSpace util.MinFreeSpace, idxDir string, diskType types.DiskType) *DiskLocation {
 	dir = util.ResolvePath(dir)
 	if idxDir == "" {
 		idxDir = dir
diff --git a/weed/storage/store.go b/weed/storage/store.go
index ae0cfb31b..2345f7d49 100644
--- a/weed/storage/store.go
+++ b/weed/storage/store.go
@@ -70,7 +70,7 @@ func NewStore(grpcDialOption grpc.DialOption, ip string, port int, grpcPort int,
 	s = &Store{grpcDialOption: grpcDialOption, Port: port, Ip: ip, GrpcPort: grpcPort, PublicUrl: publicUrl, NeedleMapKind: needleMapKind}
 	s.Locations = make([]*DiskLocation, 0)
 	for i := 0; i < len(dirnames); i++ {
-		location := NewDiskLocation(dirnames[i], maxVolumeCounts[i], minFreeSpaces[i], idxFolder, diskTypes[i])
+		location := NewDiskLocation(dirnames[i], int32(maxVolumeCounts[i]), minFreeSpaces[i], idxFolder, diskTypes[i])
 		location.loadExistingVolumes(needleMapKind)
 		s.Locations = append(s.Locations, location)
 		stats.VolumeServerMaxVolumeCounter.Add(float64(maxVolumeCounts[i]))
@@ -116,7 +116,7 @@ func (s *Store) findVolume(vid needle.VolumeId) *Volume {
 	return nil
 }
 func (s *Store) FindFreeLocation(diskType DiskType) (ret *DiskLocation) {
-	max := 0
+	max := int32(0)
 	for _, location := range s.Locations {
 		if diskType != location.DiskType {
 			continue
@@ -124,9 +124,9 @@ func (s *Store) FindFreeLocation(diskType DiskType) (ret *DiskLocation) {
 		if location.isDiskSpaceLow {
 			continue
 		}
-		currentFreeCount := location.MaxVolumeCount - location.VolumesLen()
+		currentFreeCount := location.MaxVolumeCount - int32(location.VolumesLen())
 		currentFreeCount *= erasure_coding.DataShardsCount
-		currentFreeCount -= location.EcVolumesLen()
+		currentFreeCount -= int32(location.EcVolumesLen())
 		currentFreeCount /= erasure_coding.DataShardsCount
 		if currentFreeCount > max {
 			max = currentFreeCount
@@ -539,19 +539,19 @@ func (s *Store) MaybeAdjustVolumeMax() (hasChanges bool) {
 	}
 	for _, diskLocation := range s.Locations {
 		if diskLocation.OriginalMaxVolumeCount == 0 {
-			currentMaxVolumeCount := diskLocation.MaxVolumeCount
+			currentMaxVolumeCount := atomic.LoadInt32(&diskLocation.MaxVolumeCount)
 			diskStatus := stats.NewDiskStatus(diskLocation.Directory)
 			unusedSpace := diskLocation.UnUsedSpace(volumeSizeLimit)
 			unclaimedSpaces := int64(diskStatus.Free) - int64(unusedSpace)
 			volCount := diskLocation.VolumesLen()
-			maxVolumeCount := volCount
+			maxVolumeCount := int32(volCount)
 			if unclaimedSpaces > int64(volumeSizeLimit) {
-				maxVolumeCount += int(uint64(unclaimedSpaces)/volumeSizeLimit) - 1
+				maxVolumeCount += int32(uint64(unclaimedSpaces)/volumeSizeLimit) - 1
 			}
-			diskLocation.MaxVolumeCount = maxVolumeCount
+			atomic.StoreInt32(&diskLocation.MaxVolumeCount, maxVolumeCount)
 			glog.V(2).Infof("disk %s max %d unclaimedSpace:%dMB, unused:%dMB volumeSizeLimit:%dMB",
 				diskLocation.Directory, maxVolumeCount, unclaimedSpaces/1024/1024, unusedSpace/1024/1024, volumeSizeLimit/1024/1024)
-			hasChanges = hasChanges || currentMaxVolumeCount != diskLocation.MaxVolumeCount
+			hasChanges = hasChanges || currentMaxVolumeCount != atomic.LoadInt32(&diskLocation.MaxVolumeCount)
 		}
 	}
 	return