diff --git a/weed/command/mount_std.go b/weed/command/mount_std.go
index e2aa7e7d4..56338e327 100644
--- a/weed/command/mount_std.go
+++ b/weed/command/mount_std.go
@@ -169,11 +169,7 @@ func RunMount(option *MountOptions, umask os.FileMode) bool {
 		mountRoot = mountRoot[0 : len(mountRoot)-1]
 	}
 
-	diskType, err := storage.ToDiskType(*option.diskType)
-	if err != nil {
-		fmt.Printf("failed to parse volume type: %v\n", err)
-		return false
-	}
+	diskType := storage.ToDiskType(*option.diskType)
 
 	seaweedFileSystem := filesys.NewSeaweedFileSystem(&filesys.Option{
 		MountDirectory:     dir,
diff --git a/weed/command/volume.go b/weed/command/volume.go
index fa7dcaa06..9fadcf7df 100644
--- a/weed/command/volume.go
+++ b/weed/command/volume.go
@@ -173,11 +173,7 @@ func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, v
 	var diskTypes []storage.DiskType
 	diskTypeStrings := strings.Split(*v.diskType, ",")
 	for _, diskTypeString := range diskTypeStrings {
-		if diskType, err := storage.ToDiskType(diskTypeString); err == nil {
-			diskTypes = append(diskTypes, diskType)
-		} else {
-			glog.Fatalf("failed to parse volume type: %v", err)
-		}
+		diskTypes = append(diskTypes, storage.ToDiskType(diskTypeString))
 	}
 	if len(diskTypes) == 1 && len(v.folders) > 1 {
 		for i := 0; i < len(v.folders)-1; i++ {
diff --git a/weed/server/master_grpc_server_volume.go b/weed/server/master_grpc_server_volume.go
index f1d65896a..deac3027c 100644
--- a/weed/server/master_grpc_server_volume.go
+++ b/weed/server/master_grpc_server_volume.go
@@ -61,10 +61,7 @@ func (ms *MasterServer) Assign(ctx context.Context, req *master_pb.AssignRequest
 	if err != nil {
 		return nil, err
 	}
-	diskType, err := storage.ToDiskType(req.DiskType)
-	if err != nil {
-		return nil, err
-	}
+	diskType := storage.ToDiskType(req.DiskType)
 
 	option := &topology.VolumeGrowOption{
 		Collection:         req.Collection,
diff --git a/weed/server/master_server_handlers_admin.go b/weed/server/master_server_handlers_admin.go
index 7b1ec1f87..28737324c 100644
--- a/weed/server/master_server_handlers_admin.go
+++ b/weed/server/master_server_handlers_admin.go
@@ -158,10 +158,7 @@ func (ms *MasterServer) getVolumeGrowOption(r *http.Request) (*topology.VolumeGr
 	if err != nil {
 		return nil, err
 	}
-	diskType, err := storage.ToDiskType(r.FormValue("disk"))
-	if err != nil {
-		return nil, err
-	}
+	diskType := storage.ToDiskType(r.FormValue("disk"))
 
 	preallocate := ms.preallocateSize
 	if r.FormValue("preallocate") != "" {
diff --git a/weed/storage/volume_type.go b/weed/storage/volume_disk_type.go
similarity index 64%
rename from weed/storage/volume_type.go
rename to weed/storage/volume_disk_type.go
index 3e8d5ffb5..e97002120 100644
--- a/weed/storage/volume_type.go
+++ b/weed/storage/volume_disk_type.go
@@ -1,6 +1,8 @@
 package storage
 
-import "fmt"
+import (
+	"strings"
+)
 
 type DiskType string
 
@@ -9,7 +11,8 @@ const (
 	SsdType                = "ssd"
 )
 
-func ToDiskType(vt string) (diskType DiskType, err error) {
+func ToDiskType(vt string) (diskType DiskType) {
+	vt = strings.ToLower(vt)
 	diskType = HardDriveType
 	switch vt {
 	case "", "hdd":
@@ -17,7 +20,7 @@ func ToDiskType(vt string) (diskType DiskType, err error) {
 	case "ssd":
 		diskType = SsdType
 	default:
-		err = fmt.Errorf("parse DiskType %s: expecting hdd or ssd\n", vt)
+		diskType = DiskType(vt)
 	}
 	return
 }
diff --git a/weed/topology/topology.go b/weed/topology/topology.go
index 486394f7a..220be4e88 100644
--- a/weed/topology/topology.go
+++ b/weed/topology/topology.go
@@ -188,14 +188,14 @@ func (t *Topology) DeleteLayout(collectionName string, rp *super_block.ReplicaPl
 }
 
 func (t *Topology) RegisterVolumeLayout(v storage.VolumeInfo, dn *DataNode) {
-	diskType, _ := storage.ToDiskType(v.DiskType)
+	diskType := storage.ToDiskType(v.DiskType)
 	vl := t.GetVolumeLayout(v.Collection, v.ReplicaPlacement, v.Ttl, diskType)
 	vl.RegisterVolume(&v, dn)
 	vl.EnsureCorrectWritables(&v)
 }
 func (t *Topology) UnRegisterVolumeLayout(v storage.VolumeInfo, dn *DataNode) {
 	glog.Infof("removing volume info: %+v", v)
-	diskType, _ := storage.ToDiskType(v.DiskType)
+	diskType := storage.ToDiskType(v.DiskType)
 	volumeLayout := t.GetVolumeLayout(v.Collection, v.ReplicaPlacement, v.Ttl, diskType)
 	volumeLayout.UnRegisterVolume(&v, dn)
 	if volumeLayout.isEmpty() {
@@ -235,7 +235,7 @@ func (t *Topology) SyncDataNodeRegistration(volumes []*master_pb.VolumeInformati
 		t.UnRegisterVolumeLayout(v, dn)
 	}
 	for _, v := range changedVolumes {
-		diskType, _ := storage.ToDiskType(v.DiskType)
+		diskType := storage.ToDiskType(v.DiskType)
 		vl := t.GetVolumeLayout(v.Collection, v.ReplicaPlacement, v.Ttl, diskType)
 		vl.EnsureCorrectWritables(&v)
 	}
diff --git a/weed/topology/topology_event_handling.go b/weed/topology/topology_event_handling.go
index 5b9facc14..d4076af5d 100644
--- a/weed/topology/topology_event_handling.go
+++ b/weed/topology/topology_event_handling.go
@@ -37,7 +37,7 @@ func (t *Topology) StartRefreshWritableVolumes(grpcDialOption grpc.DialOption, g
 	}()
 }
 func (t *Topology) SetVolumeCapacityFull(volumeInfo storage.VolumeInfo) bool {
-	diskType, _ := storage.ToDiskType(volumeInfo.DiskType)
+	diskType := storage.ToDiskType(volumeInfo.DiskType)
 	vl := t.GetVolumeLayout(volumeInfo.Collection, volumeInfo.ReplicaPlacement, volumeInfo.Ttl, diskType)
 	if !vl.SetVolumeCapacityFull(volumeInfo.Id) {
 		return false
@@ -56,7 +56,7 @@ func (t *Topology) SetVolumeCapacityFull(volumeInfo storage.VolumeInfo) bool {
 func (t *Topology) UnRegisterDataNode(dn *DataNode) {
 	for _, v := range dn.GetVolumes() {
 		glog.V(0).Infoln("Removing Volume", v.Id, "from the dead volume server", dn.Id())
-		diskType, _ := storage.ToDiskType(v.DiskType)
+		diskType := storage.ToDiskType(v.DiskType)
 		vl := t.GetVolumeLayout(v.Collection, v.ReplicaPlacement, v.Ttl, diskType)
 		vl.SetVolumeUnavailable(dn, v.Id)
 	}