diff --git a/weed/command/server.go b/weed/command/server.go
index a99d5a858..4c39b099a 100644
--- a/weed/command/server.go
+++ b/weed/command/server.go
@@ -55,6 +55,8 @@ var (
 	serverDisableHttp         = cmdServer.Flag.Bool("disableHttp", false, "disable http requests, only gRPC operations are allowed.")
 	volumeDataFolders         = cmdServer.Flag.String("dir", os.TempDir(), "directories to store data files. dir[,dir]...")
 	volumeMaxDataVolumeCounts = cmdServer.Flag.String("volume.max", "7", "maximum numbers of volumes, count[,count]... If set to zero on non-windows OS, the limit will be auto configured.")
+	volumeFreeDiskSpaceWatermark = cmdServer.Flag.String("volume.freeDiskSpaceWatermark", "0", "minimum free disk space(in percents). If free disk space lower this value - all volumes marks as ReadOnly")
+
 	// pulseSeconds              = cmdServer.Flag.Int("pulseSeconds", 5, "number of seconds between heartbeats")
 	isStartingFiler           = cmdServer.Flag.Bool("filer", false, "whether to start filer")
 	isStartingS3              = cmdServer.Flag.Bool("s3", false, "whether to start S3 gateway")
@@ -206,7 +208,8 @@ func runServer(cmd *Command, args []string) bool {
 
 	// start volume server
 	{
-		go serverOptions.v.startVolumeServer(*volumeDataFolders, *volumeMaxDataVolumeCounts, *serverWhiteListOption)
+		go serverOptions.v.startVolumeServer(*volumeDataFolders, *volumeMaxDataVolumeCounts, *serverWhiteListOption, *volumeFreeDiskSpaceWatermark)
+
 	}
 
 	startMaster(masterOptions, serverWhiteList)
diff --git a/weed/command/volume.go b/weed/command/volume.go
index bb63a1f86..7f976192a 100644
--- a/weed/command/volume.go
+++ b/weed/command/volume.go
@@ -52,6 +52,7 @@ type VolumeServerOptions struct {
 	memProfile            *string
 	compactionMBPerSecond *int
 	fileSizeLimitMB       *int
+	freeDiskSpaceWatermark []float32
 }
 
 func init() {
@@ -87,6 +88,7 @@ var (
 	volumeFolders         = cmdVolume.Flag.String("dir", os.TempDir(), "directories to store data files. dir[,dir]...")
 	maxVolumeCounts       = cmdVolume.Flag.String("max", "7", "maximum numbers of volumes, count[,count]... If set to zero on non-windows OS, the limit will be auto configured.")
 	volumeWhiteListOption = cmdVolume.Flag.String("whiteList", "", "comma separated Ip addresses having write permission. No limit if empty.")
+	freeDiskSpaceWatermark = cmdVolume.Flag.String("freeDiskSpaceWatermark", "0", "minimum free disk space(in percents). If free disk space lower this value - all volumes marks as ReadOnly")
 )
 
 func runVolume(cmd *Command, args []string) bool {
@@ -96,12 +98,12 @@ func runVolume(cmd *Command, args []string) bool {
 	runtime.GOMAXPROCS(runtime.NumCPU())
 	grace.SetupProfiling(*v.cpuProfile, *v.memProfile)
 
-	v.startVolumeServer(*volumeFolders, *maxVolumeCounts, *volumeWhiteListOption)
+	v.startVolumeServer(*volumeFolders, *maxVolumeCounts, *volumeWhiteListOption, *freeDiskSpaceWatermark)
 
 	return true
 }
 
-func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, volumeWhiteListOption string) {
+func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, volumeWhiteListOption, freeDiskSpaceWatermark string) {
 
 	// Set multiple folders and each folder's max volume count limit'
 	v.folders = strings.Split(volumeFolders, ",")
@@ -116,6 +118,16 @@ func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, v
 	if len(v.folders) != len(v.folderMaxLimits) {
 		glog.Fatalf("%d directories by -dir, but only %d max is set by -max", len(v.folders), len(v.folderMaxLimits))
 	}
+	freeDiskSpaceWatermarkStrings := strings.Split(freeDiskSpaceWatermark, ",")
+	for _, freeString := range freeDiskSpaceWatermarkStrings {
+
+		if value, e := strconv.ParseFloat(freeString, 32); e == nil {
+			v.freeDiskSpaceWatermark = append(v.freeDiskSpaceWatermark, float32(value))
+		} else {
+			glog.Fatalf("The value specified in -freeDiskSpaceWatermark not a valid value %s", freeString)
+		}
+	}
+
 	for _, folder := range v.folders {
 		if err := util.TestFolderWritable(folder); err != nil {
 			glog.Fatalf("Check Data Folder(-dir) Writable %s : %s", folder, err)
@@ -159,7 +171,7 @@ func (v VolumeServerOptions) startVolumeServer(volumeFolders, maxVolumeCounts, v
 
 	volumeServer := weed_server.NewVolumeServer(volumeMux, publicVolumeMux,
 		*v.ip, *v.port, *v.publicUrl,
-		v.folders, v.folderMaxLimits,
+		v.folders, v.folderMaxLimits, v.freeDiskSpaceWatermark,
 		volumeNeedleMapKind,
 		strings.Split(masters, ","), 5, *v.dataCenter, *v.rack,
 		v.whiteList,
diff --git a/weed/server/volume_server.go b/weed/server/volume_server.go
index 2d716edc1..86e02cd92 100644
--- a/weed/server/volume_server.go
+++ b/weed/server/volume_server.go
@@ -35,7 +35,7 @@ type VolumeServer struct {
 
 func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 	port int, publicUrl string,
-	folders []string, maxCounts []int,
+	folders []string, maxCounts []int, freeDiskSpaceWatermark []float32,
 	needleMapKind storage.NeedleMapType,
 	masterNodes []string, pulseSeconds int,
 	dataCenter string, rack string,
@@ -68,8 +68,7 @@ func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 		fileSizeLimitBytes:      int64(fileSizeLimitMB) * 1024 * 1024,
 	}
 	vs.SeedMasterNodes = masterNodes
-	vs.store = storage.NewStore(vs.grpcDialOption, port, ip, publicUrl, folders, maxCounts, vs.needleMapKind)
-
+	vs.store = storage.NewStore(vs.grpcDialOption, port, ip, publicUrl, folders, maxCounts, freeDiskSpaceWatermark, vs.needleMapKind)
 	vs.guard = security.NewGuard(whiteList, signingKey, expiresAfterSec, readSigningKey, readExpiresAfterSec)
 
 	handleStaticResources(adminMux)
diff --git a/weed/storage/disk_location.go b/weed/storage/disk_location.go
index 088763c45..ba4d25635 100644
--- a/weed/storage/disk_location.go
+++ b/weed/storage/disk_location.go
@@ -1,11 +1,14 @@
 package storage
 
 import (
-	"fmt"
-	"io/ioutil"
-	"os"
-	"strings"
-	"sync"
+ 	"fmt"
+	"github.com/chrislusf/seaweedfs/weed/stats"
+ 	"io/ioutil"
+ 	"os"
+	"path/filepath"
+ 	"strings"
+ 	"sync"
+	"time"
 
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/storage/erasure_coding"
@@ -15,6 +18,7 @@ import (
 type DiskLocation struct {
 	Directory      string
 	MaxVolumeCount int
+	FreeDiskSpaceWatermark float32
 	volumes        map[needle.VolumeId]*Volume
 	volumesLock    sync.RWMutex
 
@@ -23,10 +27,11 @@ type DiskLocation struct {
 	ecVolumesLock sync.RWMutex
 }
 
-func NewDiskLocation(dir string, maxVolumeCount int) *DiskLocation {
-	location := &DiskLocation{Directory: dir, MaxVolumeCount: maxVolumeCount}
+func NewDiskLocation(dir string, maxVolumeCount int, freeDiskSpaceWatermark float32) *DiskLocation {
+	location := &DiskLocation{Directory: dir, MaxVolumeCount: maxVolumeCount, FreeDiskSpaceWatermark: freeDiskSpaceWatermark}
 	location.volumes = make(map[needle.VolumeId]*Volume)
 	location.ecVolumes = make(map[needle.VolumeId]*erasure_coding.EcVolume)
+	go location.CheckDiskSpace()
 	return location
 }
 
@@ -293,3 +298,21 @@ func (l *DiskLocation) UnUsedSpace(volumeSizeLimit uint64) (unUsedSpace uint64)
 
 	return
 }
+
+func (l *DiskLocation) CheckDiskSpace() {
+	lastStat := false
+	t := time.NewTicker(time.Minute)
+	for _ = range t.C {
+		if dir, e := filepath.Abs(l.Directory); e == nil {
+			s := stats.NewDiskStatus(dir)
+			if (s.PercentFree < l.FreeDiskSpaceWatermark) != lastStat {
+				lastStat = !lastStat
+				for _, v := range l.volumes {
+					v.SetLowDiskSpace(lastStat)
+				}
+
+			}
+		}
+	}
+
+}
\ No newline at end of file
diff --git a/weed/storage/store.go b/weed/storage/store.go
index 14881ffde..2aff8c93f 100644
--- a/weed/storage/store.go
+++ b/weed/storage/store.go
@@ -48,11 +48,11 @@ func (s *Store) String() (str string) {
 	return
 }
 
-func NewStore(grpcDialOption grpc.DialOption, port int, ip, publicUrl string, dirnames []string, maxVolumeCounts []int, needleMapKind NeedleMapType) (s *Store) {
+func NewStore(grpcDialOption grpc.DialOption, port int, ip, publicUrl string, dirnames []string, maxVolumeCounts []int, freeDiskSpaceWatermark []float32, needleMapKind NeedleMapType) (s *Store) {
 	s = &Store{grpcDialOption: grpcDialOption, Port: port, Ip: ip, PublicUrl: publicUrl, NeedleMapType: needleMapKind}
 	s.Locations = make([]*DiskLocation, 0)
 	for i := 0; i < len(dirnames); i++ {
-		location := NewDiskLocation(dirnames[i], maxVolumeCounts[i])
+		location := NewDiskLocation(dirnames[i], maxVolumeCounts[i], freeDiskSpaceWatermark[i])
 		location.loadExistingVolumes(needleMapKind)
 		s.Locations = append(s.Locations, location)
 		stats.VolumeServerMaxVolumeCounter.Add(float64(maxVolumeCounts[i]))
diff --git a/weed/storage/volume.go b/weed/storage/volume.go
index df63360a1..e10f5afaa 100644
--- a/weed/storage/volume.go
+++ b/weed/storage/volume.go
@@ -27,6 +27,7 @@ type Volume struct {
 	needleMapKind      NeedleMapType
 	noWriteOrDelete    bool // if readonly, either noWriteOrDelete or noWriteCanDelete
 	noWriteCanDelete   bool // if readonly, either noWriteOrDelete or noWriteCanDelete
+	lowDiskSpace       bool
 	hasRemoteFile      bool // if the volume has a remote file
 	MemoryMapMaxSizeMb uint32
 
@@ -45,6 +46,11 @@ type Volume struct {
 	volumeInfo *volume_server_pb.VolumeInfo
 }
 
+func (v *Volume) SetLowDiskSpace(lowDiskSpace bool) {
+	glog.V(0).Infof("SetLowDiskSpace id %d value %t", v.Id, lowDiskSpace)
+	v.lowDiskSpace = lowDiskSpace
+}
+
 func NewVolume(dirname string, collection string, id needle.VolumeId, needleMapKind NeedleMapType, replicaPlacement *super_block.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, MemoryMapMaxSizeMb: memoryMapMaxSizeMb,
@@ -244,5 +250,5 @@ func (v *Volume) RemoteStorageNameKey() (storageName, storageKey string) {
 }
 
 func (v *Volume) IsReadOnly() bool {
-	return v.noWriteOrDelete || v.noWriteCanDelete
+	return v.noWriteOrDelete || v.noWriteCanDelete || v.lowDiskSpace
 }
diff --git a/weed/topology/data_node.go b/weed/topology/data_node.go
index 0dccdd0f2..d18dd6af0 100644
--- a/weed/topology/data_node.go
+++ b/weed/topology/data_node.go
@@ -41,7 +41,7 @@ func (dn *DataNode) String() string {
 	return fmt.Sprintf("Node:%s, volumes:%v, Ip:%s, Port:%d, PublicUrl:%s", dn.NodeImpl.String(), dn.volumes, dn.Ip, dn.Port, dn.PublicUrl)
 }
 
-func (dn *DataNode) AddOrUpdateVolume(v storage.VolumeInfo) (isNew bool) {
+func (dn *DataNode) AddOrUpdateVolume(v storage.VolumeInfo) (isNew, isChangedRO bool) {
 	dn.Lock()
 	defer dn.Unlock()
 	if oldV, ok := dn.volumes[v.Id]; !ok {
@@ -64,12 +64,13 @@ func (dn *DataNode) AddOrUpdateVolume(v storage.VolumeInfo) (isNew bool) {
 				dn.UpAdjustRemoteVolumeCountDelta(-1)
 			}
 		}
+		isChangedRO = dn.volumes[v.Id].ReadOnly != v.ReadOnly
 		dn.volumes[v.Id] = v
 	}
 	return
 }
 
-func (dn *DataNode) UpdateVolumes(actualVolumes []storage.VolumeInfo) (newVolumes, deletedVolumes []storage.VolumeInfo) {
+func (dn *DataNode) UpdateVolumes(actualVolumes []storage.VolumeInfo) (newVolumes, deletedVolumes, changeRO []storage.VolumeInfo) {
 	actualVolumeMap := make(map[needle.VolumeId]storage.VolumeInfo)
 	for _, v := range actualVolumes {
 		actualVolumeMap[v.Id] = v
@@ -91,10 +92,13 @@ func (dn *DataNode) UpdateVolumes(actualVolumes []storage.VolumeInfo) (newVolume
 	}
 	dn.Unlock()
 	for _, v := range actualVolumes {
-		isNew := dn.AddOrUpdateVolume(v)
+		isNew, isChangedRO := dn.AddOrUpdateVolume(v)
 		if isNew {
 			newVolumes = append(newVolumes, v)
 		}
+		if isChangedRO {
+			changeRO = append(changeRO, v)
+		}
 	}
 	return
 }
diff --git a/weed/topology/topology.go b/weed/topology/topology.go
index c24cab9d6..993f444a7 100644
--- a/weed/topology/topology.go
+++ b/weed/topology/topology.go
@@ -212,13 +212,18 @@ func (t *Topology) SyncDataNodeRegistration(volumes []*master_pb.VolumeInformati
 		}
 	}
 	// find out the delta volumes
-	newVolumes, deletedVolumes = dn.UpdateVolumes(volumeInfos)
+	var changedVolumes []storage.VolumeInfo
+	newVolumes, deletedVolumes, changedVolumes = dn.UpdateVolumes(volumeInfos)
 	for _, v := range newVolumes {
 		t.RegisterVolumeLayout(v, dn)
 	}
 	for _, v := range deletedVolumes {
 		t.UnRegisterVolumeLayout(v, dn)
 	}
+	for _, v := range changedVolumes {
+		vl := t.GetVolumeLayout(v.Collection, v.ReplicaPlacement, v.Ttl)
+		vl.ensureCorrectWritables(&v)
+	}
 	return
 }