diff --git a/etc/ledis.json b/etc/ledis.json
index 1631303..89eb922 100644
--- a/etc/ledis.json
+++ b/etc/ledis.json
@@ -6,7 +6,8 @@
             "block_size": 32768,
             "write_buffer_size": 67108864,
             "cache_size": 524288000,
-            "max_open_files":1024         
+            "max_open_files":1024,
+            "map_size" : 524288000        
     },
 
     "access_log" : "access.log"
diff --git a/ledis/config.go b/ledis/config.go
index 5c2c1c1..ffe64d5 100644
--- a/ledis/config.go
+++ b/ledis/config.go
@@ -15,6 +15,7 @@ type Config struct {
 		WriteBufferSize int  `json:"write_buffer_size"`
 		CacheSize       int  `json:"cache_size"`
 		MaxOpenFiles    int  `json:"max_open_files"`
+		MapSize         int  `json:"map_size"`
 	} `json:"db"`
 
 	BinLog struct {
diff --git a/server/config.go b/server/config.go
index 13ab286..96fbd1a 100644
--- a/server/config.go
+++ b/server/config.go
@@ -18,6 +18,7 @@ type Config struct {
 		WriteBufferSize int  `json:"write_buffer_size"`
 		CacheSize       int  `json:"cache_size"`
 		MaxOpenFiles    int  `json:"max_open_files"`
+		MapSize         int  `json:"map_size"`
 	} `json:"db"`
 
 	BinLog struct {
diff --git a/store/config.go b/store/config.go
index b2939dc..16666a2 100644
--- a/store/config.go
+++ b/store/config.go
@@ -1,17 +1,17 @@
 package store
 
 type Config struct {
-	Name string
+	Name string `json:"name"`
 
-	Path string
+	Path string `json:"path"`
 
 	//for leveldb, goleveldb
-	Compression     bool
-	BlockSize       int
-	WriteBufferSize int
-	CacheSize       int
-	MaxOpenFiles    int
+	Compression     bool `json:"compression"`
+	BlockSize       int  `json:"block_size"`
+	WriteBufferSize int  `json:"write_buffer_size"`
+	CacheSize       int  `json:"cache_size"`
+	MaxOpenFiles    int  `json:"max_open_files"`
 
 	//for lmdb
-	MapSize int
+	MapSize int `json:"map_size"`
 }
diff --git a/store/mdb/batch.go b/store/mdb/batch.go
index 60b6812..d8debf6 100644
--- a/store/mdb/batch.go
+++ b/store/mdb/batch.go
@@ -27,6 +27,6 @@ func (w *WriteBatch) Commit() error {
 }
 
 func (w *WriteBatch) Rollback() error {
-	w.wb = []Write{}
+	w.wb = w.wb[0:0]
 	return nil
 }
diff --git a/store/mdb/mdb.go b/store/mdb/mdb.go
index 038121a..a737c6a 100644
--- a/store/mdb/mdb.go
+++ b/store/mdb/mdb.go
@@ -20,7 +20,7 @@ type MDB struct {
 func Open(c *Config) (MDB, error) {
 	path := c.Path
 	if c.MapSize == 0 {
-		c.MapSize = 10 * 1024 * 1024
+		c.MapSize = 1024 * 1024 * 1024
 	}
 
 	env, err := mdb.NewEnv()
@@ -43,7 +43,7 @@ func Open(c *Config) (MDB, error) {
 		}
 	}
 
-	err = env.Open(path, mdb.WRITEMAP|mdb.MAPASYNC|mdb.CREATE, 0755)
+	err = env.Open(path, mdb.NOSYNC|mdb.NOMETASYNC|mdb.WRITEMAP|mdb.MAPASYNC|mdb.CREATE, 0755)
 	if err != nil {
 		return MDB{}, err
 	}
@@ -77,7 +77,12 @@ func Repair(c *Config) error {
 }
 
 func (db MDB) Put(key, value []byte) error {
-	return db.BatchPut([]Write{{key, value}})
+	itr := db.iterator(false)
+	defer itr.Close()
+
+	itr.err = itr.c.Put(key, value, 0)
+	itr.setState()
+	return itr.Error()
 }
 
 func (db MDB) BatchPut(writes []Write) error {
@@ -118,13 +123,14 @@ func (db MDB) Get(key []byte) ([]byte, error) {
 
 func (db MDB) Delete(key []byte) error {
 	itr := db.iterator(false)
+	defer itr.Close()
 
 	itr.key, itr.value, itr.err = itr.c.Get(key, mdb.SET)
 	if itr.err == nil {
 		itr.err = itr.c.Del(0)
 	}
 	itr.setState()
-	return itr.Close()
+	return itr.Error()
 }
 
 type MDBIterator struct {