diff --git a/include/libs/sync/sync.h b/include/libs/sync/sync.h
index 2e04afdbdc8d06029808da29398392f481832d75..a587ad6ef22fb80538147a61980ae4cdadd8ec03 100644
--- a/include/libs/sync/sync.h
+++ b/include/libs/sync/sync.h
@@ -66,12 +66,6 @@ typedef struct SSyncCfg {
   SNodeInfo nodeInfo[TSDB_MAX_REPLICA];
 } SSyncCfg;
 
-typedef struct SSnapshot {
-  void*     data;
-  SyncIndex lastApplyIndex;
-  SyncTerm  lastApplyTerm;
-} SSnapshot;
-
 typedef struct SFsmCbMeta {
   SyncIndex  index;
   bool       isWeak;
@@ -93,6 +87,12 @@ typedef struct SReConfigCbMeta {
   uint64_t  flag;
 } SReConfigCbMeta;
 
+typedef struct SSnapshot {
+  void *data;
+  SyncIndex lastApplyIndex;
+  SyncTerm  lastApplyTerm;
+} SSnapshot;
+
 typedef struct SSyncFSM {
   void* data;
 
@@ -101,23 +101,17 @@ typedef struct SSyncFSM {
   void (*FpRollBackCb)(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta);
 
   void (*FpRestoreFinishCb)(struct SSyncFSM* pFsm);
-  int32_t (*FpGetSnapshot)(struct SSyncFSM* pFsm, SSnapshot* pSnapshot);
-
-  // if (*ppIter == NULL)
-  //   *ppIter = new iter;
-  // else
-  //   *ppIter.next();
-  //
-  // if success, return 0. else return error code
-  int32_t (*FpSnapshotRead)(struct SSyncFSM* pFsm, const SSnapshot* pSnapshot, void** ppIter, char** ppBuf,
-                            int32_t* len);
+  void (*FpReConfigCb)(struct SSyncFSM* pFsm, SSyncCfg newCfg, SReConfigCbMeta cbMeta);
 
-  // apply data into fsm
-  int32_t (*FpSnapshotApply)(struct SSyncFSM* pFsm, const SSnapshot* pSnapshot, char* pBuf, int32_t len);
+  int32_t (*FpGetSnapshot)(struct SSyncFSM* pFsm, SSnapshot* pSnapshot);
 
-  void (*FpReConfigCb)(struct SSyncFSM* pFsm, SSyncCfg newCfg, SReConfigCbMeta cbMeta);
+  int32_t (*FpSnapshotStartRead)(struct SSyncFSM* pFsm, void** ppReader);
+  int32_t (*FpSnapshotStopRead)(struct SSyncFSM* pFsm, void* pReader);
+  int32_t (*FpSnapshotDoRead)(struct SSyncFSM* pFsm, void* pReader, void** ppBuf, int32_t* len);
 
-  // int32_t (*FpRestoreSnapshot)(struct SSyncFSM* pFsm, const SSnapshot* snapshot);
+  int32_t (*FpSnapshotStartWrite)(struct SSyncFSM* pFsm, void** ppWriter);
+  int32_t (*FpSnapshotStopWrite)(struct SSyncFSM* pFsm, void* pWriter, bool isApply);
+  int32_t (*FpSnapshotDoWrite)(struct SSyncFSM* pFsm, void* pWriter, void* pBuf, int32_t len);
 
 } SSyncFSM;
 
diff --git a/source/dnode/mnode/impl/src/mndSync.c b/source/dnode/mnode/impl/src/mndSync.c
index d5fcf9b1eb9bbc93ba623b09bbe3b8ff459b6240..ecf7cabc134fa4c607af876182d8334220ffe2b7 100644
--- a/source/dnode/mnode/impl/src/mndSync.c
+++ b/source/dnode/mnode/impl/src/mndSync.c
@@ -105,6 +105,8 @@ void mndReConfig(struct SSyncFSM *pFsm, SSyncCfg newCfg, SReConfigCbMeta cbMeta)
 
 SSyncFSM *mndSyncMakeFsm(SMnode *pMnode) {
   SSyncFSM *pFsm = taosMemoryCalloc(1, sizeof(SSyncFSM));
+  memset(pFsm, 0, sizeof(*pFsm));
+
   pFsm->data = pMnode;
 
   pFsm->FpCommitCb = mndSyncCommitMsg;
@@ -113,8 +115,6 @@ SSyncFSM *mndSyncMakeFsm(SMnode *pMnode) {
 
   pFsm->FpGetSnapshot = mndSyncGetSnapshot;
   pFsm->FpRestoreFinishCb = mndRestoreFinish;
-  pFsm->FpSnapshotRead = mndSnapshotRead;
-  pFsm->FpSnapshotApply = mndSnapshotApply;
   pFsm->FpReConfigCb = mndReConfig;
   
   return pFsm;
diff --git a/source/dnode/vnode/src/vnd/vnodeSync.c b/source/dnode/vnode/src/vnd/vnodeSync.c
index d8f3110a16fbd118e966a34d2d8d8d8c58519f54..240b478ac0797d8e03a8311b637bc28f81d1c670 100644
--- a/source/dnode/vnode/src/vnd/vnodeSync.c
+++ b/source/dnode/vnode/src/vnd/vnodeSync.c
@@ -142,14 +142,13 @@ void vnodeSyncRollBackMsg(SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta
 
 SSyncFSM *vnodeSyncMakeFsm(SVnode *pVnode) {
   SSyncFSM *pFsm = taosMemoryCalloc(1, sizeof(SSyncFSM));
+  memset(pFsm, 0, sizeof(*pFsm));
   pFsm->data = pVnode;
   pFsm->FpCommitCb = vnodeSyncCommitMsg;
   pFsm->FpPreCommitCb = vnodeSyncPreCommitMsg;
   pFsm->FpRollBackCb = vnodeSyncRollBackMsg;
   pFsm->FpGetSnapshot = vnodeSyncGetSnapshot;
   pFsm->FpRestoreFinishCb = NULL;
-  pFsm->FpSnapshotRead = NULL;
-  pFsm->FpSnapshotApply = NULL;
   pFsm->FpReConfigCb = NULL;
 
   return pFsm;
diff --git a/source/libs/sync/inc/syncSnapshot.h b/source/libs/sync/inc/syncSnapshot.h
index b3174a4b36855b417ababbb0c4614867433a2e83..43d1c0c0c38bc9836fdb9e3210f141af44376700 100644
--- a/source/libs/sync/inc/syncSnapshot.h
+++ b/source/libs/sync/inc/syncSnapshot.h
@@ -28,10 +28,12 @@ extern "C" {
 #include "taosdef.h"
 
 typedef struct SSyncSnapshotSender {
-  bool       isStart;
-  int32_t    progressIndex;
+  int32_t    sending;
+  int32_t    received;
+  bool       finish;
   void *     pCurrentBlock;
-  int32_t    len;
+  int32_t    blockLen;
+  int64_t    sendingMS;
   SSnapshot *pSnapshot;
   SSyncNode *pSyncNode;
 } SSyncSnapshotSender;
@@ -43,7 +45,8 @@ cJSON *              snapshotSender2Json(SSyncSnapshotSender *pSender);
 char *               snapshotSender2Str(SSyncSnapshotSender *pSender);
 
 typedef struct SSyncSnapshotReceiver {
-  bool       isStart;
+  bool       start;
+  int32_t    received;
   int32_t    progressIndex;
   void *     pCurrentBlock;
   int32_t    len;
diff --git a/source/libs/sync/src/syncRaftCfg.c b/source/libs/sync/src/syncRaftCfg.c
index 70481b853ece4ba5cab45f303184042494b44609..86a07ca4f8a9846801510ad5763f687a4db290b3 100644
--- a/source/libs/sync/src/syncRaftCfg.c
+++ b/source/libs/sync/src/syncRaftCfg.c
@@ -58,8 +58,8 @@ int32_t raftCfgPersist(SRaftCfg *pRaftCfg) {
   int64_t ret = taosWriteFile(pRaftCfg->pFile, buf, sizeof(buf));
   assert(ret == sizeof(buf));
 
-  //int64_t ret = taosWriteFile(pRaftCfg->pFile, s, strlen(s) + 1);
-  //assert(ret == strlen(s) + 1);
+  // int64_t ret = taosWriteFile(pRaftCfg->pFile, s, strlen(s) + 1);
+  // assert(ret == strlen(s) + 1);
 
   taosMemoryFree(s);
   taosFsyncFile(pRaftCfg->pFile);
@@ -170,7 +170,7 @@ int32_t raftCfgCreateFile(SSyncCfg *pCfg, int8_t isStandBy, const char *path) {
   SRaftCfg raftCfg;
   raftCfg.cfg = *pCfg;
   raftCfg.isStandBy = isStandBy;
-  char *  s = raftCfg2Str(&raftCfg);
+  char *s = raftCfg2Str(&raftCfg);
 
   char buf[CONFIG_FILE_LEN];
   memset(buf, 0, sizeof(buf));
@@ -179,8 +179,8 @@ int32_t raftCfgCreateFile(SSyncCfg *pCfg, int8_t isStandBy, const char *path) {
   int64_t ret = taosWriteFile(pFile, buf, sizeof(buf));
   assert(ret == sizeof(buf));
 
-  //int64_t ret = taosWriteFile(pFile, s, strlen(s) + 1);
-  //assert(ret == strlen(s) + 1);
+  // int64_t ret = taosWriteFile(pFile, s, strlen(s) + 1);
+  // assert(ret == strlen(s) + 1);
 
   taosMemoryFree(s);
   taosCloseFile(&pFile);
diff --git a/source/libs/sync/test/syncConfigChangeTest.cpp b/source/libs/sync/test/syncConfigChangeTest.cpp
index 1755b7a8fd967fa5db22b4fdc523cc3f771d3c4b..2880d8951484e3ee51eb10d05cda159a90129e8f 100644
--- a/source/libs/sync/test/syncConfigChangeTest.cpp
+++ b/source/libs/sync/test/syncConfigChangeTest.cpp
@@ -84,14 +84,15 @@ void ReConfigCb(struct SSyncFSM* pFsm, SSyncCfg newCfg, SReConfigCbMeta cbMeta)
 
 SSyncFSM* createFsm() {
   SSyncFSM* pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(SSyncFSM));
+  memset(pFsm, 0, sizeof(*pFsm));
+
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
 
   pFsm->FpGetSnapshot = GetSnapshotCb;
   pFsm->FpRestoreFinishCb = RestoreFinishCb;
-  pFsm->FpSnapshotApply = NULL;
-  pFsm->FpSnapshotRead = NULL;
+
 
   pFsm->FpReConfigCb = ReConfigCb;
 
diff --git a/source/libs/sync/test/syncSnapshotTest.cpp b/source/libs/sync/test/syncSnapshotTest.cpp
index 8ccd69890708781dbfb5b4a3ae835acc5c17d15c..820500e2d8f8b57427fec1f20741755a2ddc2d5c 100644
--- a/source/libs/sync/test/syncSnapshotTest.cpp
+++ b/source/libs/sync/test/syncSnapshotTest.cpp
@@ -75,6 +75,7 @@ int32_t GetSnapshotCb(struct SSyncFSM *pFsm, SSnapshot *pSnapshot) {
 
 void initFsm() {
   pFsm = (SSyncFSM *)taosMemoryMalloc(sizeof(SSyncFSM));
+  memset(pFsm, 0, sizeof(*pFsm));
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;