diff --git a/weed-fs/src/cmd/weed/fix.go b/weed-fs/src/cmd/weed/fix.go
index 7bed70edd..53b6cfc75 100644
--- a/weed-fs/src/cmd/weed/fix.go
+++ b/weed-fs/src/cmd/weed/fix.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"errors"
 	"log"
 	"os"
 	"path"
@@ -33,24 +34,36 @@ func runFix(cmd *Command, args []string) bool {
 	}
 
 	fileName := strconv.Itoa(*volumeId)
-	dataFile, e := os.OpenFile(path.Join(*dir, fileName+".dat"), os.O_RDONLY, 0644)
+
+	if err := createIndexFile(path.Join(*dir, fileName+".dat")); err != nil {
+		log.Fatalf("[ERROR] " + err.Error())
+	}
+	return true
+}
+
+func createIndexFile(datafn string) error {
+	dataFile, e := os.OpenFile(datafn, os.O_RDONLY, 0644)
 	if e != nil {
-		log.Fatalf("Read Volume [ERROR] %s\n", e)
+		return errors.New("Read Volume " + e.Error())
 	}
 	defer dataFile.Close()
-	indexFile, ie := os.OpenFile(path.Join(*dir, fileName+".idx"), os.O_WRONLY|os.O_CREATE, 0644)
+	// log.Printf("dataFile=%s", dataFile)
+	indexFile, ie := os.OpenFile(datafn[:len(datafn)-4]+".idx", os.O_WRONLY|os.O_CREATE, 0644)
 	if ie != nil {
-		log.Fatalf("Create Volume Index [ERROR] %s\n", ie)
+		return errors.New("Create Volume Index " + ie.Error())
 	}
 	defer indexFile.Close()
 
 	dataFile.Seek(0, 0)
 	header := make([]byte, storage.SuperBlockSize)
 	if _, e := dataFile.Read(header); e != nil {
-		log.Fatalf("cannot read superblock: %s", e)
+		return errors.New("cannot read superblock: " + e.Error())
 	}
 
-	ver, _, _ := storage.ParseSuperBlock(header)
+	ver, _, e := storage.ParseSuperBlock(header)
+	if e != nil {
+		return errors.New("cannot parse superblock: " + e.Error())
+	}
 
 	n, rest := storage.ReadNeedleHeader(dataFile, ver)
 	dataFile.Seek(int64(rest), 1)
@@ -66,5 +79,5 @@ func runFix(cmd *Command, args []string) bool {
 		n, rest = storage.ReadNeedleHeader(dataFile, ver)
 		dataFile.Seek(int64(rest), 1)
 	}
-	return true
+	return nil
 }
diff --git a/weed-fs/src/cmd/weed/weed.go b/weed-fs/src/cmd/weed/weed.go
index e2eb41ced..685027fb6 100644
--- a/weed-fs/src/cmd/weed/weed.go
+++ b/weed-fs/src/cmd/weed/weed.go
@@ -21,6 +21,7 @@ var server *string
 
 var commands = []*Command{
 	cmdFix,
+	cmdFreeze,
 	cmdMaster,
 	cmdUpload,
 	cmdShell,
diff --git a/weed-fs/src/pkg/storage/cdb_map.go b/weed-fs/src/pkg/storage/cdb_map.go
index b80b3cde9..bffb2b9ea 100644
--- a/weed-fs/src/pkg/storage/cdb_map.go
+++ b/weed-fs/src/pkg/storage/cdb_map.go
@@ -28,7 +28,7 @@ func NewCdbMap(filename string) (*CdbMap, error) {
 // writes the content of the index file to a CDB and returns that
 func NewCdbMapFromIndex(indexFile *os.File) (*CdbMap, error) {
 	nm := indexFile.Name()
-	nm = nm[strings.LastIndex(nm, ".")+1:] + "cdb"
+	nm = nm[:strings.LastIndex(nm, ".")+1] + "cdb"
 
 	var (
 		key    uint64
@@ -52,12 +52,14 @@ func NewCdbMapFromIndex(indexFile *os.File) (*CdbMap, error) {
 		return nil, err
 	}
 
+	log.Printf("deleted: %s\nnm=%s", deleted, nm)
 	w, err := cdb.NewWriter(nm)
 	if err != nil {
 		return nil, err
 	}
 	iterFun := func(buf []byte) error {
 		key = util.BytesToUint64(buf[:8])
+		log.Printf("iter key=%d", key)
 		if _, ok = deleted[key]; !ok {
 			w.PutPair(buf[:8], buf[8:16])
 		}
@@ -69,6 +71,9 @@ func NewCdbMapFromIndex(indexFile *os.File) (*CdbMap, error) {
 	if err != nil {
 		return nil, err
 	}
+	if err = util.SetFilePerm(nil, nm, 0444, -1); err != nil {
+		return nil, err
+	}
 
 	return NewCdbMap(nm)
 }
diff --git a/weed-fs/src/pkg/storage/needle_map.go b/weed-fs/src/pkg/storage/needle_map.go
index f103d10d8..c1b84358c 100644
--- a/weed-fs/src/pkg/storage/needle_map.go
+++ b/weed-fs/src/pkg/storage/needle_map.go
@@ -6,6 +6,7 @@ import (
 	"log"
 	"os"
 	"pkg/util"
+	"strings"
 )
 
 type NeedleMap struct {
@@ -50,10 +51,40 @@ func NewNeedleMap(file *os.File) *NeedleMap {
 }
 
 // Nes frozen (on-disk, not modifiable(!)) needle map
-func NewFrozenNeedleMap(file *os.File) (*NeedleMap, error) {
-	fm, err := NewCdbMapFromIndex(file)
-	if err != nil {
-		return nil, err
+func NewFrozenNeedleMap(fileName string) (*NeedleMap, error) {
+	if strings.HasSuffix(fileName, ".dat") {
+		fileName = fileName[:4]
+	}
+	var (
+		fm          *CdbMap
+		indexExists bool
+	)
+	file, err := os.Open(fileName + ".idx")
+	if err != nil && os.IsNotExist(err) {
+		if fm, err = NewCdbMap(fileName + ".cdb"); err != nil {
+			log.Printf("error opening %s.cdb: %s", fileName, err)
+			fm = nil
+		} else {
+			if dstat, e := os.Stat(fileName + ".dat"); e == nil {
+				if cstat, e := os.Stat(fileName + ".cdb"); e == nil {
+					if cstat.ModTime().Before(dstat.ModTime()) {
+						return nil, errors.New("CDB file " + fileName +
+							".cdb is older than data file " + fileName + ".dat!")
+					}
+				}
+			}
+		}
+	} else {
+		indexExists = true
+	}
+	if fm == nil {
+		fm, err = NewCdbMapFromIndex(file)
+		if err != nil {
+			return nil, err
+		}
+		if indexExists {
+			os.Remove(fileName + ".idx")
+		}
 	}
 	return &NeedleMap{
 		fm:    fm,
diff --git a/weed-fs/src/pkg/storage/store.go b/weed-fs/src/pkg/storage/store.go
index b06c29902..161b855e3 100644
--- a/weed-fs/src/pkg/storage/store.go
+++ b/weed-fs/src/pkg/storage/store.go
@@ -33,6 +33,8 @@ func NewStore(port int, ip, publicUrl, dirname string, maxVolumeCount int) (s *S
 	log.Println("Store started on dir:", dirname, "with", len(s.volumes), "volumes")
 	return
 }
+
+// adds a volume to the store
 func (s *Store) AddVolume(volumeListString string, replicationType string) error {
 	rt, e := NewReplicationTypeFromString(replicationType)
 	if e != nil {
@@ -74,6 +76,7 @@ func (s *Store) addVolume(vid VolumeId, replicationType ReplicationType) (err er
 	return err
 }
 
+// checks whether compaction is needed
 func (s *Store) CheckCompactVolume(volumeIdString string, garbageThresholdString string) (error, bool) {
 	vid, err := NewVolumeId(volumeIdString)
 	if err != nil {
@@ -85,6 +88,8 @@ func (s *Store) CheckCompactVolume(volumeIdString string, garbageThresholdString
 	}
 	return nil, garbageThreshold < s.volumes[vid].garbageLevel()
 }
+
+// compacts the volume
 func (s *Store) CompactVolume(volumeIdString string) error {
 	vid, err := NewVolumeId(volumeIdString)
 	if err != nil {
@@ -92,6 +97,8 @@ func (s *Store) CompactVolume(volumeIdString string) error {
 	}
 	return s.volumes[vid].compact()
 }
+
+// commits the compaction
 func (s *Store) CommitCompactVolume(volumeIdString string) error {
 	vid, err := NewVolumeId(volumeIdString)
 	if err != nil {
@@ -99,6 +106,8 @@ func (s *Store) CommitCompactVolume(volumeIdString string) error {
 	}
 	return s.volumes[vid].commitCompact()
 }
+
+// reads directory and loads volumes
 func (s *Store) loadExistingVolumes() {
 	if dirs, err := ioutil.ReadDir(s.dir); err == nil {
 		for _, dir := range dirs {
diff --git a/weed-fs/src/pkg/storage/volume.go b/weed-fs/src/pkg/storage/volume.go
index 6a79d6c40..d694f27ba 100644
--- a/weed-fs/src/pkg/storage/volume.go
+++ b/weed-fs/src/pkg/storage/volume.go
@@ -6,6 +6,7 @@ import (
 	"log"
 	"os"
 	"path"
+	"pkg/util"
 	"sync"
 )
 
@@ -45,13 +46,18 @@ func (v *Volume) load() error {
 		v.maybeWriteSuperBlock()
 	}
 	// TODO: if .idx not exists, but .cdb exists, then use (but don't load!) that
-	indexFile, ie := os.OpenFile(fileName+".idx", os.O_RDWR|os.O_CREATE, 0644)
-	if ie != nil {
-		return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
+	if !util.FileIsWritable(v.dataFile.Name()) { //Read-Only
+		v.nm, e = NewFrozenNeedleMap(fileName)
+	} else {
+		indexFile, ie := os.OpenFile(fileName+".idx", os.O_RDWR|os.O_CREATE, 0644)
+		if ie != nil {
+			return fmt.Errorf("cannot create Volume Data %s.dat: %s", fileName, e)
+		}
+		v.nm, e = LoadNeedleMap(indexFile)
 	}
-	v.nm, e = LoadNeedleMap(indexFile)
 	return e
 }
+
 func (v *Volume) Version() Version {
 	return v.version
 }
diff --git a/weed-fs/src/pkg/util/file.go b/weed-fs/src/pkg/util/file.go
new file mode 100644
index 000000000..bf3ea66de
--- /dev/null
+++ b/weed-fs/src/pkg/util/file.go
@@ -0,0 +1,63 @@
+package util
+
+import (
+	"errors"
+	"log"
+	"os"
+)
+
+// sets file (fh if not nil, otherwise fileName) permission to mask
+// it will
+//   AND with the permission iff direction < 0
+//   OR with the permission iff direction > 0
+//   otherwise it will SET the permission to the mask
+func SetFilePerm(fh *os.File, fileName string, mask os.FileMode, direction int8) (err error) {
+	var stat os.FileInfo
+	if fh == nil {
+		stat, err = os.Stat(fileName)
+	} else {
+		stat, err = fh.Stat()
+	}
+	if err != nil {
+		return err
+	}
+
+	mode := stat.Mode() & ^os.ModePerm
+	// log.Printf("mode1=%d mask=%d", mode, mask)
+	if direction == 0 {
+		mode |= mask
+	} else if direction > 0 {
+		mode |= stat.Mode().Perm() | mask
+	} else {
+		mode |= stat.Mode().Perm() & mask
+	}
+	log.Printf("pmode=%d operm=%d => nmode=%d nperm=%d",
+		stat.Mode(), stat.Mode()&os.ModePerm,
+		mode, mode&os.ModePerm)
+	if mode == 0 {
+		return errors.New("Zero FileMode")
+	}
+	if fh == nil {
+		err = os.Chmod(fileName, mode)
+	} else {
+		err = fh.Chmod(mode)
+	}
+	return err
+}
+
+// returns whether  the filename exists - errors doesn't mean not exists!
+func FileExists(fileName string) bool {
+	if _, e := os.Stat(fileName); e != nil && os.IsNotExist(e) {
+		return false
+	}
+	return true
+}
+
+// returns whether the filename is POSSIBLY writable
+//- whether it has some kind of writable bit set
+func FileIsWritable(fileName string) bool {
+	if stat, e := os.Stat(fileName); e == nil {
+		return stat.Mode().Perm()&0222 > 0
+	}
+	return false
+}