diff --git a/weed/command/backup.go b/weed/command/backup.go
index 0b3994027..7983f7dab 100644
--- a/weed/command/backup.go
+++ b/weed/command/backup.go
@@ -75,7 +75,7 @@ func runBackup(cmd *Command, args []string) bool {
 		return true
 	}
 
-	v, err := storage.NewVolume(*s.dir, *s.collection, vid, storage.NeedleMapInMemory, replication, ttl)
+	v, err := storage.NewVolume(*s.dir, *s.collection, vid, storage.NeedleMapInMemory, replication, ttl, 0)
 	if err != nil {
 		fmt.Printf("Error creating or reading from volume %d: %v\n", vid, err)
 		return true
diff --git a/weed/command/compact.go b/weed/command/compact.go
index db11880ec..ae54db115 100644
--- a/weed/command/compact.go
+++ b/weed/command/compact.go
@@ -20,10 +20,11 @@ var cmdCompact = &Command{
 }
 
 var (
-	compactVolumePath       = cmdCompact.Flag.String("dir", ".", "data directory to store files")
-	compactVolumeCollection = cmdCompact.Flag.String("collection", "", "volume collection name")
-	compactVolumeId         = cmdCompact.Flag.Int("volumeId", -1, "a volume id. The volume should already exist in the dir.")
-	compactMethod           = cmdCompact.Flag.Int("method", 0, "option to choose which compact method. use 0 or 1.")
+	compactVolumePath        = cmdCompact.Flag.String("dir", ".", "data directory to store files")
+	compactVolumeCollection  = cmdCompact.Flag.String("collection", "", "volume collection name")
+	compactVolumeId          = cmdCompact.Flag.Int("volumeId", -1, "a volume id. The volume should already exist in the dir.")
+	compactMethod            = cmdCompact.Flag.Int("method", 0, "option to choose which compact method. use 0 or 1.")
+	compactVolumePreallocate = cmdCompact.Flag.Int64("preallocate", 0, "preallocate volume disk space")
 )
 
 func runCompact(cmd *Command, args []string) bool {
@@ -34,7 +35,7 @@ func runCompact(cmd *Command, args []string) bool {
 
 	vid := storage.VolumeId(*compactVolumeId)
 	v, err := storage.NewVolume(*compactVolumePath, *compactVolumeCollection, vid,
-		storage.NeedleMapInMemory, nil, nil)
+		storage.NeedleMapInMemory, nil, nil, *compactVolumePreallocate)
 	if err != nil {
 		glog.Fatalf("Load Volume [ERROR] %s\n", err)
 	}
diff --git a/weed/command/master.go b/weed/command/master.go
index cd15defce..ec54fbd7b 100644
--- a/weed/command/master.go
+++ b/weed/command/master.go
@@ -35,6 +35,7 @@ var (
 	metaFolder              = cmdMaster.Flag.String("mdir", os.TempDir(), "data directory to store meta data")
 	masterPeers             = cmdMaster.Flag.String("peers", "", "other master nodes in comma separated ip:port list, example: 127.0.0.1:9093,127.0.0.1:9094")
 	volumeSizeLimitMB       = cmdMaster.Flag.Uint("volumeSizeLimitMB", 30*1000, "Master stops directing writes to oversized volumes.")
+	volumePreallocate       = cmdMaster.Flag.Bool("volumePreallocate", false, "Preallocate disk space for volumes.")
 	mpulse                  = cmdMaster.Flag.Int("pulseSeconds", 5, "number of seconds between heartbeats")
 	confFile                = cmdMaster.Flag.String("conf", "/etc/weedfs/weedfs.conf", "Deprecating! xml configuration file")
 	defaultReplicaPlacement = cmdMaster.Flag.String("defaultReplication", "000", "Default replication type if not specified.")
@@ -73,7 +74,8 @@ func runMaster(cmd *Command, args []string) bool {
 
 	r := mux.NewRouter()
 	ms := weed_server.NewMasterServer(r, *mport, *metaFolder,
-		*volumeSizeLimitMB, *mpulse, *confFile, *defaultReplicaPlacement, *garbageThreshold,
+		*volumeSizeLimitMB, *volumePreallocate,
+		*mpulse, *confFile, *defaultReplicaPlacement, *garbageThreshold,
 		masterWhiteList, *masterSecureKey,
 	)
 
diff --git a/weed/command/server.go b/weed/command/server.go
index 027ba191d..87146940f 100644
--- a/weed/command/server.go
+++ b/weed/command/server.go
@@ -61,6 +61,7 @@ var (
 	masterPort                    = cmdServer.Flag.Int("master.port", 9333, "master server http listen port")
 	masterMetaFolder              = cmdServer.Flag.String("master.dir", "", "data directory to store meta data, default to same as -dir specified")
 	masterVolumeSizeLimitMB       = cmdServer.Flag.Uint("master.volumeSizeLimitMB", 30*1000, "Master stops directing writes to oversized volumes.")
+	masterVolumePreallocate       = cmdServer.Flag.Bool("master.volumePreallocate", false, "Preallocate disk space for volumes.")
 	masterConfFile                = cmdServer.Flag.String("master.conf", "/etc/weedfs/weedfs.conf", "xml configuration file")
 	masterDefaultReplicaPlacement = cmdServer.Flag.String("master.defaultReplicaPlacement", "000", "Default replication type if not specified.")
 	volumePort                    = cmdServer.Flag.Int("volume.port", 8080, "volume server http listen port")
@@ -204,7 +205,8 @@ func runServer(cmd *Command, args []string) bool {
 	go func() {
 		r := mux.NewRouter()
 		ms := weed_server.NewMasterServer(r, *masterPort, *masterMetaFolder,
-			*masterVolumeSizeLimitMB, *volumePulse, *masterConfFile, *masterDefaultReplicaPlacement, *serverGarbageThreshold,
+			*masterVolumeSizeLimitMB, *masterVolumePreallocate,
+			*volumePulse, *masterConfFile, *masterDefaultReplicaPlacement, *serverGarbageThreshold,
 			serverWhiteList, *serverSecureKey,
 		)
 
diff --git a/weed/server/master_server.go b/weed/server/master_server.go
index 61bda6988..9f59c2400 100644
--- a/weed/server/master_server.go
+++ b/weed/server/master_server.go
@@ -20,6 +20,7 @@ type MasterServer struct {
 	port                    int
 	metaFolder              string
 	volumeSizeLimitMB       uint
+	preallocate             int64
 	pulseSeconds            int
 	defaultReplicaPlacement string
 	garbageThreshold        string
@@ -34,6 +35,7 @@ type MasterServer struct {
 
 func NewMasterServer(r *mux.Router, port int, metaFolder string,
 	volumeSizeLimitMB uint,
+	preallocate bool,
 	pulseSeconds int,
 	confFile string,
 	defaultReplicaPlacement string,
@@ -41,9 +43,15 @@ func NewMasterServer(r *mux.Router, port int, metaFolder string,
 	whiteList []string,
 	secureKey string,
 ) *MasterServer {
+
+	var preallocateSize int64
+	if preallocate {
+		preallocateSize = int64(volumeSizeLimitMB) * (1 << 20)
+	}
 	ms := &MasterServer{
 		port:                    port,
 		volumeSizeLimitMB:       volumeSizeLimitMB,
+		preallocate:             preallocateSize,
 		pulseSeconds:            pulseSeconds,
 		defaultReplicaPlacement: defaultReplicaPlacement,
 		garbageThreshold:        garbageThreshold,
diff --git a/weed/server/master_server_handlers_admin.go b/weed/server/master_server_handlers_admin.go
index a762bf416..efe81bf89 100644
--- a/weed/server/master_server_handlers_admin.go
+++ b/weed/server/master_server_handlers_admin.go
@@ -181,10 +181,18 @@ func (ms *MasterServer) getVolumeGrowOption(r *http.Request) (*topology.VolumeGr
 	if err != nil {
 		return nil, err
 	}
+	preallocate := ms.preallocate
+	if r.FormValue("preallocate") != "" {
+		preallocate, err = strconv.ParseInt(r.FormValue("preallocate"), 10, 64)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to parse int64 preallocate = %s: %v", r.FormValue("preallocate"), err)
+		}
+	}
 	volumeGrowOption := &topology.VolumeGrowOption{
 		Collection:       r.FormValue("collection"),
 		ReplicaPlacement: replicaPlacement,
 		Ttl:              ttl,
+		Prealloacte:      preallocate,
 		DataCenter:       r.FormValue("dataCenter"),
 		Rack:             r.FormValue("rack"),
 		DataNode:         r.FormValue("dataNode"),
diff --git a/weed/server/volume_server_handlers_admin.go b/weed/server/volume_server_handlers_admin.go
index ae9817ef6..28631dac7 100644
--- a/weed/server/volume_server_handlers_admin.go
+++ b/weed/server/volume_server_handlers_admin.go
@@ -3,6 +3,7 @@ package weed_server
 import (
 	"net/http"
 	"path/filepath"
+	"strconv"
 
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/stats"
@@ -17,13 +18,29 @@ func (vs *VolumeServer) statusHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func (vs *VolumeServer) assignVolumeHandler(w http.ResponseWriter, r *http.Request) {
-	err := vs.store.AddVolume(r.FormValue("volume"), r.FormValue("collection"), vs.needleMapKind, r.FormValue("replication"), r.FormValue("ttl"))
+	var err error
+	preallocate := int64(0)
+	if r.FormValue("preallocate") != "" {
+		preallocate, err = strconv.ParseInt(r.FormValue("preallocate"), 10, 64)
+		if err != nil {
+			glog.V(0).Infoln("ignoring invalid int64 value for preallocate = %v", r.FormValue("preallocate"))
+		}
+	}
+	err = vs.store.AddVolume(
+		r.FormValue("volume"),
+		r.FormValue("collection"),
+		vs.needleMapKind,
+		r.FormValue("replication"),
+		r.FormValue("ttl"),
+		preallocate,
+	)
 	if err == nil {
 		writeJsonQuiet(w, r, http.StatusAccepted, map[string]string{"error": ""})
 	} else {
 		writeJsonError(w, r, http.StatusNotAcceptable, err)
 	}
-	glog.V(2).Infoln("assign volume =", r.FormValue("volume"), ", collection =", r.FormValue("collection"), ", replication =", r.FormValue("replication"), ", error =", err)
+	glog.V(2).Infoln("assign volume = %s, collection = %s , replication = %s, error = %v",
+		r.FormValue("volume"), r.FormValue("collection"), r.FormValue("replication"), err)
 }
 
 func (vs *VolumeServer) deleteCollectionHandler(w http.ResponseWriter, r *http.Request) {
@@ -33,7 +50,7 @@ func (vs *VolumeServer) deleteCollectionHandler(w http.ResponseWriter, r *http.R
 	} else {
 		writeJsonError(w, r, http.StatusInternalServerError, err)
 	}
-	glog.V(2).Infoln("deleting collection =", r.FormValue("collection"), ", error =", err)
+	glog.V(2).Infof("deleting collection = %s, error = %v", r.FormValue("collection"), err)
 }
 
 func (vs *VolumeServer) statsDiskHandler(w http.ResponseWriter, r *http.Request) {
diff --git a/weed/storage/disk_location.go b/weed/storage/disk_location.go
index 039b4f3b9..496e0dd57 100644
--- a/weed/storage/disk_location.go
+++ b/weed/storage/disk_location.go
@@ -36,7 +36,7 @@ func (l *DiskLocation) loadExistingVolume(dir os.FileInfo, needleMapKind NeedleM
 			_, found := l.volumes[vid]
 			mutex.RUnlock()
 			if !found {
-				if v, e := NewVolume(l.Directory, collection, vid, needleMapKind, nil, nil); e == nil {
+				if v, e := NewVolume(l.Directory, collection, vid, needleMapKind, nil, nil, 0); e == nil {
 					mutex.Lock()
 					l.volumes[vid] = v
 					mutex.Unlock()
diff --git a/weed/storage/needle_read_write.go b/weed/storage/needle_read_write.go
index ff43effb3..4f03ce396 100644
--- a/weed/storage/needle_read_write.go
+++ b/weed/storage/needle_read_write.go
@@ -146,18 +146,13 @@ func (n *Needle) Append(w io.Writer, version Version) (size uint32, actualSize i
 		util.Uint32toBytes(header[0:NeedleChecksumSize], n.Checksum.Value())
 		_, err = w.Write(header[0 : NeedleChecksumSize+padding])
 
-		actualSize = NeedleHeaderSize + int64(n.Size) + NeedleChecksumSize + int64(padding)
-
-		return n.DataSize, actualSize, err
+		return n.DataSize, getActualSize(n.Size), err
 	}
 	return 0, 0, fmt.Errorf("Unsupported Version! (%d)", version)
 }
 
 func ReadNeedleBlob(r *os.File, offset int64, size uint32) (dataSlice []byte, block *Block, err error) {
-	NeedleWithoutPaddingSize := NeedleHeaderSize + size + NeedleChecksumSize
-	padding := NeedlePaddingSize - (NeedleWithoutPaddingSize % NeedlePaddingSize)
-	readSize := NeedleWithoutPaddingSize + padding
-	return getBytesForFileBlock(r, offset, int(readSize))
+	return getBytesForFileBlock(r, offset, int(getActualSize(size)))
 }
 
 func (n *Needle) ReadData(r *os.File, offset int64, size uint32, version Version) (err error) {
diff --git a/weed/storage/store.go b/weed/storage/store.go
index 37a3904bd..be2044d64 100644
--- a/weed/storage/store.go
+++ b/weed/storage/store.go
@@ -95,7 +95,7 @@ func NewStore(port int, ip, publicUrl string, dirnames []string, maxVolumeCounts
 	}
 	return
 }
-func (s *Store) AddVolume(volumeListString string, collection string, needleMapKind NeedleMapType, replicaPlacement string, ttlString string) error {
+func (s *Store) AddVolume(volumeListString string, collection string, needleMapKind NeedleMapType, replicaPlacement string, ttlString string, preallocate int64) error {
 	rt, e := NewReplicaPlacementFromString(replicaPlacement)
 	if e != nil {
 		return e
@@ -111,7 +111,7 @@ func (s *Store) AddVolume(volumeListString string, collection string, needleMapK
 			if err != nil {
 				return fmt.Errorf("Volume Id %s is not a valid unsigned integer!", id_string)
 			}
-			e = s.addVolume(VolumeId(id), collection, needleMapKind, rt, ttl)
+			e = s.addVolume(VolumeId(id), collection, needleMapKind, rt, ttl, preallocate)
 		} else {
 			pair := strings.Split(range_string, "-")
 			start, start_err := strconv.ParseUint(pair[0], 10, 64)
@@ -123,7 +123,7 @@ func (s *Store) AddVolume(volumeListString string, collection string, needleMapK
 				return fmt.Errorf("Volume End Id %s is not a valid unsigned integer!", pair[1])
 			}
 			for id := start; id <= end; id++ {
-				if err := s.addVolume(VolumeId(id), collection, needleMapKind, rt, ttl); err != nil {
+				if err := s.addVolume(VolumeId(id), collection, needleMapKind, rt, ttl, preallocate); err != nil {
 					e = err
 				}
 			}
@@ -160,14 +160,14 @@ func (s *Store) findFreeLocation() (ret *DiskLocation) {
 	}
 	return ret
 }
-func (s *Store) addVolume(vid VolumeId, collection string, needleMapKind NeedleMapType, replicaPlacement *ReplicaPlacement, ttl *TTL) error {
+func (s *Store) addVolume(vid VolumeId, collection string, needleMapKind NeedleMapType, replicaPlacement *ReplicaPlacement, ttl *TTL, preallocate int64) error {
 	if s.findVolume(vid) != nil {
 		return fmt.Errorf("Volume Id %d already exists!", vid)
 	}
 	if location := s.findFreeLocation(); location != nil {
 		glog.V(0).Infof("In dir %s adds volume:%v collection:%s replicaPlacement:%v ttl:%v",
 			location.Directory, vid, collection, replicaPlacement, ttl)
-		if volume, err := NewVolume(location.Directory, collection, vid, needleMapKind, replicaPlacement, ttl); err == nil {
+		if volume, err := NewVolume(location.Directory, collection, vid, needleMapKind, replicaPlacement, ttl, preallocate); err == nil {
 			location.SetVolume(vid, volume)
 			return nil
 		} else {
diff --git a/weed/storage/volume.go b/weed/storage/volume.go
index 11ee600df..df9f0b7a7 100644
--- a/weed/storage/volume.go
+++ b/weed/storage/volume.go
@@ -29,11 +29,11 @@ type Volume struct {
 	lastCompactRevision    uint16
 }
 
-func NewVolume(dirname string, collection string, id VolumeId, needleMapKind NeedleMapType, replicaPlacement *ReplicaPlacement, ttl *TTL) (v *Volume, e error) {
+func NewVolume(dirname string, collection string, id VolumeId, needleMapKind NeedleMapType, replicaPlacement *ReplicaPlacement, ttl *TTL, preallocate int64) (v *Volume, e error) {
 	v = &Volume{dir: dirname, Collection: collection, Id: id}
 	v.SuperBlock = SuperBlock{ReplicaPlacement: replicaPlacement, Ttl: ttl}
 	v.needleMapKind = needleMapKind
-	e = v.load(true, true, needleMapKind)
+	e = v.load(true, true, needleMapKind, preallocate)
 	return
 }
 func (v *Volume) String() string {
diff --git a/weed/storage/volume_create.go b/weed/storage/volume_create.go
new file mode 100644
index 000000000..6b3a17439
--- /dev/null
+++ b/weed/storage/volume_create.go
@@ -0,0 +1,17 @@
+// +build !linux
+
+package storage
+
+import (
+	"os"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+)
+
+func createVolumeFile(fileName string, preallocate int64) (file *os.File, e error) {
+	file, e = os.OpenFile(fileName, os.O_RDWR|os.O_CREATE, 0644)
+	if preallocate > 0 {
+		glog.V(0).Infof("Preallocated disk space for %s is not supported", fileName)
+	}
+	return file, e
+}
diff --git a/weed/storage/volume_create_linux.go b/weed/storage/volume_create_linux.go
new file mode 100644
index 000000000..8f6bab2fe
--- /dev/null
+++ b/weed/storage/volume_create_linux.go
@@ -0,0 +1,19 @@
+// +build linux
+
+package storage
+
+import (
+	"os"
+	"syscall"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+)
+
+func createVolumeFile(fileName string, preallocate int64) (file *os.File, e error) {
+	file, e = os.OpenFile(fileName, os.O_RDWR|os.O_CREATE, 0644)
+	if preallocate != 0 {
+		syscall.Fallocate(int(file.Fd()), 1, 0, preallocate)
+		glog.V(0).Infof("Preallocated %d bytes disk space for %s", preallocate, fileName)
+	}
+	return file, e
+}
diff --git a/weed/storage/volume_loading.go b/weed/storage/volume_loading.go
index 7bc65a4a3..c4f1aae9b 100644
--- a/weed/storage/volume_loading.go
+++ b/weed/storage/volume_loading.go
@@ -12,11 +12,11 @@ func loadVolumeWithoutIndex(dirname string, collection string, id VolumeId, need
 	v = &Volume{dir: dirname, Collection: collection, Id: id}
 	v.SuperBlock = SuperBlock{}
 	v.needleMapKind = needleMapKind
-	e = v.load(false, false, needleMapKind)
+	e = v.load(false, false, needleMapKind, 0)
 	return
 }
 
-func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool, needleMapKind NeedleMapType) error {
+func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool, needleMapKind NeedleMapType, preallocate int64) error {
 	var e error
 	fileName := v.FileName()
 
@@ -34,7 +34,7 @@ func (v *Volume) load(alsoLoadIndex bool, createDatIfMissing bool, needleMapKind
 		}
 	} else {
 		if createDatIfMissing {
-			v.dataFile, e = os.OpenFile(fileName+".dat", os.O_RDWR|os.O_CREATE, 0644)
+			v.dataFile, e = createVolumeFile(fileName+".dat", preallocate)
 		} 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 f3ded5ff2..13072d1fb 100644
--- a/weed/storage/volume_vacuum.go
+++ b/weed/storage/volume_vacuum.go
@@ -24,7 +24,7 @@ func (v *Volume) Compact() error {
 	v.lastCompactIndexOffset = v.nm.IndexFileSize()
 	v.lastCompactRevision = v.SuperBlock.CompactRevision
 	glog.V(3).Infof("creating copies for volume %d ,last offset %d...", v.Id, v.lastCompactIndexOffset)
-	return v.copyDataAndGenerateIndexFile(filePath+".cpd", filePath+".cpx")
+	return v.copyDataAndGenerateIndexFile(filePath+".cpd", filePath+".cpx", v.dataFileSize)
 }
 
 func (v *Volume) Compact2() error {
@@ -66,7 +66,7 @@ func (v *Volume) commitCompact() error {
 	//glog.V(3).Infof("Pretending to be vacuuming...")
 	//time.Sleep(20 * time.Second)
 	glog.V(3).Infof("Loading Commit file...")
-	if e = v.load(true, false, v.needleMapKind); e != nil {
+	if e = v.load(true, false, v.needleMapKind, 0); e != nil {
 		return e
 	}
 	return nil
@@ -207,11 +207,11 @@ func (v *Volume) makeupDiff(newDatFileName, newIdxFileName, oldDatFileName, oldI
 	return nil
 }
 
-func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string) (err error) {
+func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string, preallocate int64) (err error) {
 	var (
 		dst, idx *os.File
 	)
-	if dst, err = os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
+	if dst, err = createVolumeFile(dstName, preallocate); err != nil {
 		return
 	}
 	defer dst.Close()
diff --git a/weed/topology/allocate_volume.go b/weed/topology/allocate_volume.go
index 7b267a805..ebf8ecbf0 100644
--- a/weed/topology/allocate_volume.go
+++ b/weed/topology/allocate_volume.go
@@ -20,6 +20,7 @@ func AllocateVolume(dn *DataNode, vid storage.VolumeId, option *VolumeGrowOption
 	values.Add("collection", option.Collection)
 	values.Add("replication", option.ReplicaPlacement.String())
 	values.Add("ttl", option.Ttl.String())
+	values.Add("preallocate", fmt.Sprintf("%d", option.Prealloacte))
 	jsonBlob, err := util.Post("http://"+dn.Url()+"/admin/assign_volume", values)
 	if err != nil {
 		return err
diff --git a/weed/topology/volume_growth.go b/weed/topology/volume_growth.go
index 3a1c9c567..ddf687419 100644
--- a/weed/topology/volume_growth.go
+++ b/weed/topology/volume_growth.go
@@ -21,6 +21,7 @@ type VolumeGrowOption struct {
 	Collection       string
 	ReplicaPlacement *storage.ReplicaPlacement
 	Ttl              *storage.TTL
+	Prealloacte      int64
 	DataCenter       string
 	Rack             string
 	DataNode         string