diff --git a/weed/storage/volume.go b/weed/storage/volume.go
index 7d1a2802a..afe3b4c8a 100644
--- a/weed/storage/volume.go
+++ b/weed/storage/volume.go
@@ -18,14 +18,14 @@ import (
 )
 
 type Volume struct {
-	Id            needle.VolumeId
-	dir           string
-	Collection    string
-	dataFile      *os.File
-	nm            NeedleMapper
-	needleMapKind NeedleMapType
-	readOnly      bool
-	MemoryMapped  uint32
+	Id                 needle.VolumeId
+	dir                string
+	Collection         string
+	dataFile           *os.File
+	nm                 NeedleMapper
+	needleMapKind      NeedleMapType
+	readOnly           bool
+	MemoryMapMaxSizeMB uint32
 
 	SuperBlock
 
@@ -39,9 +39,9 @@ type Volume struct {
 	isCompacting bool
 }
 
-func NewVolume(dirname string, collection string, id needle.VolumeId, needleMapKind NeedleMapType, replicaPlacement *ReplicaPlacement, ttl *needle.TTL, preallocate int64, memoryMapped uint32) (v *Volume, e error) {
+func NewVolume(dirname string, collection string, id needle.VolumeId, needleMapKind NeedleMapType, replicaPlacement *ReplicaPlacement, ttl *needle.TTL, preallocate int64, memoryMapMaxSizeMB uint32) (v *Volume, e error) {
 	// if replicaPlacement is nil, the superblock will be loaded from disk
-	v = &Volume{dir: dirname, Collection: collection, Id: id, MemoryMapped: memoryMapped}
+	v = &Volume{dir: dirname, Collection: collection, Id: id, MemoryMapMaxSizeMB: memoryMapMaxSizeMB}
 	v.SuperBlock = SuperBlock{ReplicaPlacement: replicaPlacement, Ttl: ttl}
 	v.needleMapKind = needleMapKind
 	e = v.load(true, true, needleMapKind, preallocate)
diff --git a/weed/storage/volume_loading.go b/weed/storage/volume_loading.go
index bdf9984e5..49bbcd22b 100644
--- a/weed/storage/volume_loading.go
+++ b/weed/storage/volume_loading.go
@@ -42,7 +42,7 @@ func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool, needleMapKind
 		}
 	} else {
 		if createDatIfMissing {
-			v.dataFile, e = createVolumeFile(fileName+".dat", preallocate, v.MemoryMapped)
+			v.dataFile, e = createVolumeFile(fileName+".dat", preallocate, v.MemoryMapMaxSizeMB)
 		} else {
 			return fmt.Errorf("Volume Data file %s.dat does not exist.", fileName)
 		}
diff --git a/weed/storage/volume_vacuum.go b/weed/storage/volume_vacuum.go
index 301c8bb0e..1b47f0483 100644
--- a/weed/storage/volume_vacuum.go
+++ b/weed/storage/volume_vacuum.go
@@ -23,7 +23,7 @@ func (v *Volume) garbageLevel() float64 {
 
 func (v *Volume) Compact(preallocate int64, compactionBytePerSecond int64) error {
 
-	if v.MemoryMapped > 0 { //it makes no sense to compact in memory
+	if v.MemoryMapMaxSizeMB > 0 { //it makes no sense to compact in memory
 		glog.V(3).Infof("Compacting volume %d ...", v.Id)
 		//no need to lock for copy on write
 		//v.accessLock.Lock()
@@ -46,7 +46,7 @@ func (v *Volume) Compact(preallocate int64, compactionBytePerSecond int64) error
 
 func (v *Volume) Compact2() error {
 
-	if v.MemoryMapped > 0 { //it makes no sense to compact in memory
+	if v.MemoryMapMaxSizeMB > 0 { //it makes no sense to compact in memory
 		glog.V(3).Infof("Compact2 volume %d ...", v.Id)
 
 		v.isCompacting = true
@@ -63,7 +63,7 @@ func (v *Volume) Compact2() error {
 }
 
 func (v *Volume) CommitCompact() error {
-	if v.MemoryMapped>0 { //it makes no sense to compact in memory
+	if v.MemoryMapMaxSizeMB > 0 { //it makes no sense to compact in memory
 		glog.V(0).Infof("Committing volume %d vacuuming...", v.Id)
 
 		v.isCompacting = true
@@ -311,7 +311,7 @@ func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string, prealloca
 	var (
 		dst, idx *os.File
 	)
-	if dst, err = createVolumeFile(dstName, preallocate, v.MemoryMapped); err != nil {
+	if dst, err = createVolumeFile(dstName, preallocate, v.MemoryMapMaxSizeMB); err != nil {
 		return
 	}
 	defer dst.Close()