diff --git a/weed-fs/src/cmd/weeds.go b/weed-fs/src/cmd/weeds.go
index 0a1b78f0e..b41a5d437 100644
--- a/weed-fs/src/cmd/weeds.go
+++ b/weed-fs/src/cmd/weeds.go
@@ -18,6 +18,7 @@ var (
 	capacity   = flag.Int("capacity", 100, "maximum number of volumes to hold")
 	mapper     *directory.Mapper
 	IsDebug    = flag.Bool("debug", false, "verbose debug information")
+	volumeSizeLimitMB = flag.Uint("volumeSizeLimitMB", 32*1024, "Default Volume Size in MegaBytes")
 )
 
 func dirLookupHandler(w http.ResponseWriter, r *http.Request) {
@@ -69,12 +70,11 @@ func writeJson(w http.ResponseWriter, r *http.Request, obj interface{}) {
 		fmt.Fprint(w, string(bytes))
 		w.Write([]uint8(")"))
 	}
-	//log.Println("JSON Response", string(bytes))
 }
 
 func main() {
 	flag.Parse()
-	mapper = directory.NewMapper(*metaFolder, "directory")
+	mapper = directory.NewMapper(*metaFolder, "directory", uint32(*volumeSizeLimitMB*1024*1024))
 	http.HandleFunc("/dir/assign", dirAssignHandler)
 	http.HandleFunc("/dir/lookup", dirLookupHandler)
 	http.HandleFunc("/dir/join", dirJoinHandler)
diff --git a/weed-fs/src/pkg/directory/volume_mapping.go b/weed-fs/src/pkg/directory/volume_mapping.go
index a51294411..828975b97 100644
--- a/weed-fs/src/pkg/directory/volume_mapping.go
+++ b/weed-fs/src/pkg/directory/volume_mapping.go
@@ -12,7 +12,6 @@ import (
 )
 
 const (
-	ChunkSizeLimit     = 32 * 1024 * 1024 //32G, can not be more than max(uint32)*8
 	FileIdSaveInterval = 10000
 )
 
@@ -36,15 +35,18 @@ type Mapper struct {
 
 	FileIdSequence uint64
 	fileIdCounter  uint64
+	
+	volumeSizeLimit uint32
 }
 
 func NewMachine(server, publicUrl string, volumes []storage.VolumeInfo) *Machine {
 	return &Machine{Server: MachineInfo{Url: server, PublicUrl: publicUrl}, Volumes: volumes}
 }
 
-func NewMapper(dirname string, filename string) (m *Mapper) {
+func NewMapper(dirname string, filename string, volumeSizeLimit uint32) (m *Mapper) {
 	m = &Mapper{dir: dirname, fileName: filename}
 	m.vid2machineId = make(map[uint32]int)
+	m.volumeSizeLimit = volumeSizeLimit
 	m.Writers = *new([]int)
 	m.Machines = *new([]*Machine)
 
@@ -116,7 +118,7 @@ func (m *Mapper) Add(machine Machine){
 	var writers []int
 	for machine_index, machine_entry := range m.Machines {
 		for _, v := range machine_entry.Volumes {
-			if v.Size < ChunkSizeLimit {
+			if v.Size < int64(m.volumeSizeLimit) {
 				writers = append(writers, machine_index)
 			}
 		}