diff --git a/go/filer/redis_store/directory_manager.go b/go/filer/redis_store/directory_manager.go
index 138cd918e..bf66a5a30 100644
--- a/go/filer/redis_store/directory_manager.go
+++ b/go/filer/redis_store/directory_manager.go
@@ -3,6 +3,7 @@ package redis_store
 import (
 	"fmt"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -86,26 +87,38 @@ func (dm *DirectoryManager) MakeDirectory(dirPath string) (filer.DirectoryId, er
 }
 
 //delete directory dirPath and its sub-directories recursively;
-//it's not this function's responsibility to check whether dirPath is empty.
+//it's not this function's responsibility to check whether dirPath is en empty directory.
 func (dm *DirectoryManager) DeleteDirectory(dirPath string) error {
 	dirPath = embedded_filer.CleanFilePath(dirPath)
 	if dirPath == "/" {
 		return fmt.Errorf("Can not delete %s", dirPath)
 	}
+	dirPathParent := filepath.Dir(dirPath)
+	dirPathName := filepath.Base(dirPath)
+	/*
+		lua comments:
+			1. delete dirPath's sub-directories recursively
+			2. delete dirPath itself from its parent dir
+
+	*/
 	script := redis.NewScript(`
 		local delSubs
 		delSubs = function(dir) 
 			local subs=redis.call('hgetall', dir); 
 			for i, v in ipairs(subs) do 
 				if i%2 ~= 0 then 
+					redis.call('hdel', dir, v)
 					local subd=dir..'/'..v; 
 					delSubs(subd); 
 				end 
 			end 
 		end
 		delSubs(KEYS[1])
+		redis.call('hdel', KEYS[2], KEYS[3])
+		return 0
 	`)
-	err := script.Run(dm.Client, []string{dm.dirKeyPrefix + dirPath}, nil).Err()
+	//we do not use lua to get dirPath's parent dir and its basename, so do it in golang
+	err := script.Run(dm.Client, []string{dm.dirKeyPrefix + dirPath, dm.dirKeyPrefix + dirPathParent, dirPathName}, nil).Err()
 	return err
 }
 
@@ -208,6 +221,7 @@ func (dm *DirectoryManager) MoveUnderDirectory(oldDirPath string, newParentDirPa
 	return err
 }
 
+//return a dir's sub-directories, directories' name are sorted lexicographically
 func (dm *DirectoryManager) ListDirectories(dirPath string) (dirNames []filer.DirectoryEntry, err error) {
 	dirPath = embedded_filer.CleanFilePath(dirPath)
 	result, le := dm.Client.HGetAllMap(dm.dirKeyPrefix + dirPath).Result()
@@ -215,7 +229,16 @@ func (dm *DirectoryManager) ListDirectories(dirPath string) (dirNames []filer.Di
 		glog.Errorf("get sub-directories of %s error:%v", dirPath, err)
 		return dirNames, le
 	}
-	for k, v := range result {
+	//sort entries by directories' name
+	keys := make(sort.StringSlice, len(result))
+	i := 0
+	for k, _ := range result {
+		keys[i] = k
+		i++
+	}
+	keys.Sort()
+	for _, k := range keys {
+		v := result[k]
 		did, _ := strconv.Atoi(v)
 		entry := filer.DirectoryEntry{Name: k, Id: filer.DirectoryId(did)}
 		dirNames = append(dirNames, entry)
diff --git a/go/filer/redis_store/directory_manager_test.go b/go/filer/redis_store/directory_manager_test.go
index 30325f3cf..71fecd734 100644
--- a/go/filer/redis_store/directory_manager_test.go
+++ b/go/filer/redis_store/directory_manager_test.go
@@ -145,6 +145,41 @@ func TestDirectory(t *testing.T) {
 		t.Errorf("new dir %s has a wrong dir id:%d, 6 is expected", dir, did)
 	}
 
+	/*
+	 * list a dir's sub-directories
+	 *
+	 */
+	dir = "/a/b"
+	entries, err := dm.ListDirectories(dir)
+	if !(entries[0].Name == "d" && entries[1].Name == "f") {
+		t.Errorf("get entries:%v, expect 'd', 'f'", entries)
+	}
+	/*
+		* delete a dir: /a/b/f/e
+		 *
+	*/
+	dir = "/a/b/f"
+	err = dm.DeleteDirectory(dir)
+	if err != nil {
+		t.Errorf("delete dir:%s error:%v", dir, err)
+	}
+	// now the deleted dir should not exist
+	did, err = dm.FindDirectory(dir)
+	if err != nil {
+		t.Errorf("get deleted dir %s error:%v", dir, err)
+	}
+	if did != 0 {
+		t.Errorf("the dir %s is not deleted!", dir)
+	}
+	// now the deleted dir's sub-directory also should not exist
+	dir = "/a/b/f/e"
+	did, err = dm.FindDirectory(dir)
+	if err != nil {
+		t.Errorf("get deleted dir %s error:%v", dir, err)
+	}
+	if did != 0 {
+		t.Errorf("the dir %s is not deleted!", dir)
+	}
 }
 
 func clearRedisKeys(client *redis.Client, dirKeyPrefix string, dirMaxIdKey string) error {
diff --git a/go/filer/redis_store/redis_store.go b/go/filer/redis_store/redis_store.go
index a31f98232..59317219a 100644
--- a/go/filer/redis_store/redis_store.go
+++ b/go/filer/redis_store/redis_store.go
@@ -8,6 +8,7 @@ import (
 
 type RedisStore struct {
 	Client *redis.Client
+	dm     *DirectoryManager
 }
 
 func NewRedisStore(hostPort string, database int) *RedisStore {
@@ -16,7 +17,8 @@ func NewRedisStore(hostPort string, database int) *RedisStore {
 		Password: "", // no password set
 		DB:       int64(database),
 	})
-	return &RedisStore{Client: client}
+	dm := InitDirectoryManger(client)
+	return &RedisStore{Client: client, dm: dm}
 }
 
 /*
@@ -75,10 +77,10 @@ func (s *RedisStore) Close() {
 }
 
 func (c *RedisStore) FindDirectory(dirPath string) (dirId filer.DirectoryId, err error) {
-	return 0, flat_namespace.ErrNotImplemented
+	return c.dm.FindDirectory(dirPath)
 }
 func (c *RedisStore) ListDirectories(dirPath string) (dirs []filer.DirectoryEntry, err error) {
-	return nil, flat_namespace.ErrNotImplemented
+	return c.dm.ListDirectories(dirPath)
 }
 func (c *RedisStore) ListFiles(dirPath string, lastFileName string, limit int) (files []filer.FileEntry, err error) {
 	return nil, flat_namespace.ErrNotImplemented