diff --git a/include/common/tmsgdef.h b/include/common/tmsgdef.h
index 70145b434d3cfb23d68a80f4964dd3b62d63d502..7f7d7ea22a86758a5043ecb5f321cf11f9b61183 100644
--- a/include/common/tmsgdef.h
+++ b/include/common/tmsgdef.h
@@ -272,6 +272,8 @@ enum {
   TD_DEF_MSG_TYPE(TDMT_SYNC_HEARTBEAT, "sync-heartbeat", NULL, NULL)
   TD_DEF_MSG_TYPE(TDMT_SYNC_HEARTBEAT_REPLY, "sync-heartbeat-reply", NULL, NULL)
   TD_DEF_MSG_TYPE(TDMT_SYNC_LOCAL_CMD, "sync-local-cmd", NULL, NULL)
+  TD_DEF_MSG_TYPE(TDMT_SYNC_PRE_SNAPSHOT, "sync-pre-snapshot", NULL, NULL)
+  TD_DEF_MSG_TYPE(TDMT_SYNC_PRE_SNAPSHOT_REPLY, "sync-pre-snapshot-reply", NULL, NULL)
   TD_DEF_MSG_TYPE(TDMT_SYNC_MAX_MSG, "sync-max", NULL, NULL)
   
   TD_NEW_MSG_SEG(TDMT_VND_STREAM_MSG)
diff --git a/include/libs/sync/sync.h b/include/libs/sync/sync.h
index 67c1ffba50bbc4b662110a22a16680bcd9bd8302..694a6ef62bf907b9cad3762ad11b5199ab4fb87d 100644
--- a/include/libs/sync/sync.h
+++ b/include/libs/sync/sync.h
@@ -37,6 +37,7 @@ extern "C" {
 #define SYNC_ADD_QUORUM_COUNT        3
 #define SYNC_MNODE_LOG_RETENTION     10000
 #define SYNC_VNODE_LOG_RETENTION     100
+#define SNAPSHOT_MAX_CLOCK_SKEW_MS   1000 * 10
 
 #define SYNC_APPEND_ENTRIES_TIMEOUT_MS 10000
 
diff --git a/source/dnode/mgmt/mgmt_mnode/src/mmHandle.c b/source/dnode/mgmt/mgmt_mnode/src/mmHandle.c
index 2c4a8e9b70afe929f381e04c8aa523cc383adf2b..976f2cfd8baa221e940830d8a8d99e9e840833ce 100644
--- a/source/dnode/mgmt/mgmt_mnode/src/mmHandle.c
+++ b/source/dnode/mgmt/mgmt_mnode/src/mmHandle.c
@@ -195,6 +195,8 @@ SArray *mmGetMsgHandles() {
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_APPEND_ENTRIES_REPLY, mmPutMsgToSyncQueue, 1) == NULL) goto _OVER;
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_SNAPSHOT_SEND, mmPutMsgToSyncQueue, 1) == NULL) goto _OVER;
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_SNAPSHOT_RSP, mmPutMsgToSyncQueue, 1) == NULL) goto _OVER;
+  if (dmSetMgmtHandle(pArray, TDMT_SYNC_PRE_SNAPSHOT, mmPutMsgToSyncQueue, 1) == NULL) goto _OVER;
+  if (dmSetMgmtHandle(pArray, TDMT_SYNC_PRE_SNAPSHOT_REPLY, mmPutMsgToSyncQueue, 1) == NULL) goto _OVER;
 
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_HEARTBEAT, mmPutMsgToSyncCtrlQueue, 1) == NULL) goto _OVER;
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_HEARTBEAT_REPLY, mmPutMsgToSyncCtrlQueue, 1) == NULL) goto _OVER;
diff --git a/source/dnode/mgmt/mgmt_vnode/src/vmHandle.c b/source/dnode/mgmt/mgmt_vnode/src/vmHandle.c
index e2812e0d312704633f4ec3519ddffaa98b867700..4d6596b9d5c9521d8fa12dde3cf65267085c40a6 100644
--- a/source/dnode/mgmt/mgmt_vnode/src/vmHandle.c
+++ b/source/dnode/mgmt/mgmt_vnode/src/vmHandle.c
@@ -435,6 +435,9 @@ SArray *vmGetMsgHandles() {
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_APPEND_ENTRIES_REPLY, vmPutMsgToSyncQueue, 0) == NULL) goto _OVER;
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_SNAPSHOT_SEND, vmPutMsgToSyncQueue, 0) == NULL) goto _OVER;
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_SNAPSHOT_RSP, vmPutMsgToSyncQueue, 0) == NULL) goto _OVER;
+  if (dmSetMgmtHandle(pArray, TDMT_SYNC_PRE_SNAPSHOT, vmPutMsgToSyncQueue, 0) == NULL) goto _OVER;
+  if (dmSetMgmtHandle(pArray, TDMT_SYNC_PRE_SNAPSHOT_REPLY, vmPutMsgToSyncQueue, 0) == NULL) goto _OVER;
+
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_HEARTBEAT, vmPutMsgToSyncCtrlQueue, 0) == NULL) goto _OVER;
   if (dmSetMgmtHandle(pArray, TDMT_SYNC_HEARTBEAT_REPLY, vmPutMsgToSyncCtrlQueue, 0) == NULL) goto _OVER;
 
diff --git a/source/libs/sync/inc/syncInt.h b/source/libs/sync/inc/syncInt.h
index 1ceb45e4529fc3c6d7ed4a1e3d8adc691a5b3966..6ec29d69f5492552b1929e5cbd51ae9d794b62ce 100644
--- a/source/libs/sync/inc/syncInt.h
+++ b/source/libs/sync/inc/syncInt.h
@@ -314,6 +314,7 @@ int32_t syncNodePeerStateInit(SSyncNode* pSyncNode);
 
 // trace log
 void syncLogRecvTimer(SSyncNode* pSyncNode, const SyncTimeout* pMsg, const char* s);
+void syncLogRecvLocalCmd(SSyncNode* pSyncNode, const SyncLocalCmd* pMsg, const char* s);
 
 void syncLogSendRequestVote(SSyncNode* pSyncNode, const SyncRequestVote* pMsg, const char* s);
 void syncLogRecvRequestVote(SSyncNode* pSyncNode, const SyncRequestVote* pMsg, const char* s);
@@ -336,7 +337,17 @@ void syncLogRecvHeartbeat(SSyncNode* pSyncNode, const SyncHeartbeat* pMsg, const
 void syncLogSendHeartbeatReply(SSyncNode* pSyncNode, const SyncHeartbeatReply* pMsg, const char* s);
 void syncLogRecvHeartbeatReply(SSyncNode* pSyncNode, const SyncHeartbeatReply* pMsg, const char* s);
 
-void syncLogRecvLocalCmd(SSyncNode* pSyncNode, const SyncLocalCmd* pMsg, const char* s);
+void syncLogSendSyncPreSnapshot(SSyncNode* pSyncNode, const SyncPreSnapshot* pMsg, const char* s);
+void syncLogRecvSyncPreSnapshot(SSyncNode* pSyncNode, const SyncPreSnapshot* pMsg, const char* s);
+
+void syncLogSendSyncPreSnapshotReply(SSyncNode* pSyncNode, const SyncPreSnapshotReply* pMsg, const char* s);
+void syncLogRecvSyncPreSnapshotReply(SSyncNode* pSyncNode, const SyncPreSnapshotReply* pMsg, const char* s);
+
+void syncLogSendSyncSnapshotSend(SSyncNode* pSyncNode, const SyncSnapshotSend* pMsg, const char* s);
+void syncLogRecvSyncSnapshotSend(SSyncNode* pSyncNode, const SyncSnapshotSend* pMsg, const char* s);
+
+void syncLogSendSyncSnapshotRsp(SSyncNode* pSyncNode, const SyncSnapshotRsp* pMsg, const char* s);
+void syncLogRecvSyncSnapshotRsp(SSyncNode* pSyncNode, const SyncSnapshotRsp* pMsg, const char* s);
 
 // for debug --------------
 void syncNodePrint(SSyncNode* pObj);
diff --git a/source/libs/sync/inc/syncSnapshot.h b/source/libs/sync/inc/syncSnapshot.h
index b8b7af2dda614b9f7e53cdb64e26fc941e295472..760fc8ac733e37d9fe78647d5aaf5ea3d19c52a1 100644
--- a/source/libs/sync/inc/syncSnapshot.h
+++ b/source/libs/sync/inc/syncSnapshot.h
@@ -28,10 +28,11 @@ extern "C" {
 #include "syncMessage.h"
 #include "taosdef.h"
 
-#define SYNC_SNAPSHOT_SEQ_INVALID -1
-#define SYNC_SNAPSHOT_SEQ_FORCE_CLOSE -2
-#define SYNC_SNAPSHOT_SEQ_BEGIN 0
-#define SYNC_SNAPSHOT_SEQ_END 0x7FFFFFFF
+#define SYNC_SNAPSHOT_SEQ_INVALID      -2
+#define SYNC_SNAPSHOT_SEQ_FORCE_CLOSE  -3
+#define SYNC_SNAPSHOT_SEQ_PRE_SNAPSHOT -1
+#define SYNC_SNAPSHOT_SEQ_BEGIN        0
+#define SYNC_SNAPSHOT_SEQ_END          0x7FFFFFFF
 
 #define SYNC_SNAPSHOT_RETRY_MS 5000
 
@@ -47,19 +48,19 @@ typedef struct SSyncSnapshotSender {
   SSnapshot      snapshot;
   SSyncCfg       lastConfig;
   int64_t        sendingMS;
-  SSyncNode     *pSyncNode;
-  int32_t        replicaIndex;
   SyncTerm       term;
-  SyncTerm       privateTerm;
   int64_t        startTime;
   bool           finish;
+
+  // init when create
+  SSyncNode *pSyncNode;
+  int32_t    replicaIndex;
 } SSyncSnapshotSender;
 
 SSyncSnapshotSender *snapshotSenderCreate(SSyncNode *pSyncNode, int32_t replicaIndex);
 void                 snapshotSenderDestroy(SSyncSnapshotSender *pSender);
 bool                 snapshotSenderIsStart(SSyncSnapshotSender *pSender);
-int32_t              snapshotSenderStart(SSyncSnapshotSender *pSender, SSnapshotParam snapshotParam, SSnapshot snapshot,
-                                         void *pReader);
+int32_t              snapshotSenderStart(SSyncSnapshotSender *pSender);
 int32_t              snapshotSenderStop(SSyncSnapshotSender *pSender, bool finish);
 int32_t              snapshotSend(SSyncSnapshotSender *pSender);
 int32_t              snapshotReSend(SSyncSnapshotSender *pSender);
@@ -76,11 +77,13 @@ typedef struct SSyncSnapshotReceiver {
   int32_t        ack;
   void          *pWriter;
   SyncTerm       term;
-  SyncTerm       privateTerm;
   SSnapshotParam snapshotParam;
   SSnapshot      snapshot;
   SRaftId        fromId;
-  SSyncNode     *pSyncNode;
+  int64_t        startTime;
+
+  // init when create
+  SSyncNode *pSyncNode;
 
 } SSyncSnapshotReceiver;
 
diff --git a/source/libs/sync/inc/syncTools.h b/source/libs/sync/inc/syncTools.h
index 54fa15002aceaec5eb954a8a3557a14daf02046d..b48519a5b038ae0e0c2909ec9f83c9e595067c37 100644
--- a/source/libs/sync/inc/syncTools.h
+++ b/source/libs/sync/inc/syncTools.h
@@ -496,6 +496,69 @@ void syncHeartbeatReplyPrint2(char* s, const SyncHeartbeatReply* pMsg);
 void syncHeartbeatReplyLog(const SyncHeartbeatReply* pMsg);
 void syncHeartbeatReplyLog2(char* s, const SyncHeartbeatReply* pMsg);
 
+// ---------------------------------------------
+typedef struct SyncPreSnapshot {
+  uint32_t bytes;
+  int32_t  vgId;
+  uint32_t msgType;
+  SRaftId  srcId;
+  SRaftId  destId;
+
+  // private data
+  SyncTerm term;
+
+} SyncPreSnapshot;
+
+SyncPreSnapshot* syncPreSnapshotBuild(int32_t vgId);
+void             syncPreSnapshotDestroy(SyncPreSnapshot* pMsg);
+void             syncPreSnapshotSerialize(const SyncPreSnapshot* pMsg, char* buf, uint32_t bufLen);
+void             syncPreSnapshotDeserialize(const char* buf, uint32_t len, SyncPreSnapshot* pMsg);
+char*            syncPreSnapshotSerialize2(const SyncPreSnapshot* pMsg, uint32_t* len);
+SyncPreSnapshot* syncPreSnapshotDeserialize2(const char* buf, uint32_t len);
+void             syncPreSnapshot2RpcMsg(const SyncPreSnapshot* pMsg, SRpcMsg* pRpcMsg);
+void             syncPreSnapshotFromRpcMsg(const SRpcMsg* pRpcMsg, SyncPreSnapshot* pMsg);
+SyncPreSnapshot* syncPreSnapshotFromRpcMsg2(const SRpcMsg* pRpcMsg);
+cJSON*           syncPreSnapshot2Json(const SyncPreSnapshot* pMsg);
+char*            syncPreSnapshot2Str(const SyncPreSnapshot* pMsg);
+
+// for debug ----------------------
+void syncPreSnapshotPrint(const SyncPreSnapshot* pMsg);
+void syncPreSnapshotPrint2(char* s, const SyncPreSnapshot* pMsg);
+void syncPreSnapshotLog(const SyncPreSnapshot* pMsg);
+void syncPreSnapshotLog2(char* s, const SyncPreSnapshot* pMsg);
+
+// ---------------------------------------------
+typedef struct SyncPreSnapshotReply {
+  uint32_t bytes;
+  int32_t  vgId;
+  uint32_t msgType;
+  SRaftId  srcId;
+  SRaftId  destId;
+
+  // private data
+  SyncTerm  term;
+  SyncIndex snapStart;
+
+} SyncPreSnapshotReply;
+
+SyncPreSnapshotReply* syncPreSnapshotReplyBuild(int32_t vgId);
+void                  syncPreSnapshotReplyDestroy(SyncPreSnapshotReply* pMsg);
+void                  syncPreSnapshotReplySerialize(const SyncPreSnapshotReply* pMsg, char* buf, uint32_t bufLen);
+void                  syncPreSnapshotReplyDeserialize(const char* buf, uint32_t len, SyncPreSnapshotReply* pMsg);
+char*                 syncPreSnapshotReplySerialize2(const SyncPreSnapshotReply* pMsg, uint32_t* len);
+SyncPreSnapshotReply* syncPreSnapshotReplyDeserialize2(const char* buf, uint32_t len);
+void                  syncPreSnapshotReply2RpcMsg(const SyncPreSnapshotReply* pMsg, SRpcMsg* pRpcMsg);
+void                  syncPreSnapshotReplyFromRpcMsg(const SRpcMsg* pRpcMsg, SyncPreSnapshotReply* pMsg);
+SyncPreSnapshotReply* syncPreSnapshotReplyFromRpcMsg2(const SRpcMsg* pRpcMsg);
+cJSON*                syncPreSnapshotReply2Json(const SyncPreSnapshotReply* pMsg);
+char*                 syncPreSnapshotReply2Str(const SyncPreSnapshotReply* pMsg);
+
+// for debug ----------------------
+void syncPreSnapshotReplyPrint(const SyncPreSnapshotReply* pMsg);
+void syncPreSnapshotReplyPrint2(char* s, const SyncPreSnapshotReply* pMsg);
+void syncPreSnapshotReplyLog(const SyncPreSnapshotReply* pMsg);
+void syncPreSnapshotReplyLog2(char* s, const SyncPreSnapshotReply* pMsg);
+
 // ---------------------------------------------
 typedef struct SyncApplyMsg {
   uint32_t   bytes;
@@ -541,7 +604,7 @@ typedef struct SyncSnapshotSend {
   SyncTerm  lastTerm;         // snapshot.lastTerm
   SyncIndex lastConfigIndex;  // snapshot.lastConfigIndex
   SSyncCfg  lastConfig;
-  SyncTerm  privateTerm;
+  int64_t   startTime;
   int32_t   seq;
   uint32_t  dataLen;
   char      data[];
@@ -576,9 +639,10 @@ typedef struct SyncSnapshotRsp {
   SyncTerm  term;
   SyncIndex lastIndex;
   SyncTerm  lastTerm;
-  SyncTerm  privateTerm;
+  int64_t   startTime;
   int32_t   ack;
   int32_t   code;
+  SyncIndex snapBeginIndex;  // when ack = SYNC_SNAPSHOT_SEQ_BEGIN, it's valid
 } SyncSnapshotRsp;
 
 SyncSnapshotRsp* syncSnapshotRspBuild(int32_t vgId);
@@ -709,6 +773,9 @@ int32_t syncNodeOnRequestVoteReply(SSyncNode* ths, SyncRequestVoteReply* pMsg);
 int32_t syncNodeOnAppendEntries(SSyncNode* ths, SyncAppendEntries* pMsg);
 int32_t syncNodeOnAppendEntriesReply(SSyncNode* ths, SyncAppendEntriesReply* pMsg);
 
+int32_t syncNodeOnPreSnapshot(SSyncNode* ths, SyncPreSnapshot* pMsg);
+int32_t syncNodeOnPreSnapshotReply(SSyncNode* ths, SyncPreSnapshotReply* pMsg);
+
 int32_t syncNodeOnSnapshot(SSyncNode* ths, SyncSnapshotSend* pMsg);
 int32_t syncNodeOnSnapshotReply(SSyncNode* ths, SyncSnapshotRsp* pMsg);
 
diff --git a/source/libs/sync/src/syncAppendEntries.c b/source/libs/sync/src/syncAppendEntries.c
index 7dab112a5188256257421f2c3d3bde1ffc0bf980..4638475e716effc785f80409517b0b4391c54ba1 100644
--- a/source/libs/sync/src/syncAppendEntries.c
+++ b/source/libs/sync/src/syncAppendEntries.c
@@ -142,7 +142,6 @@ int32_t syncNodeOnAppendEntries(SSyncNode* ths, SyncAppendEntries* pMsg) {
   // pReply->matchIndex = ths->pLogStore->syncLogLastIndex(ths->pLogStore);
   pReply->matchIndex = SYNC_INDEX_INVALID;
   pReply->lastSendIndex = pMsg->prevLogIndex + 1;
-  pReply->privateTerm = ths->pNewNodeReceiver->privateTerm;
   pReply->startTime = ths->startTime;
 
   if (pMsg->term < ths->pRaftStore->currentTerm) {
diff --git a/source/libs/sync/src/syncAppendEntriesReply.c b/source/libs/sync/src/syncAppendEntriesReply.c
index 5e6c9f153422cf9e6f3baeaec8cf93ca8f0339ab..5d54db5b077c467909bbcbf81d2d3fd4d3ad7de9 100644
--- a/source/libs/sync/src/syncAppendEntriesReply.c
+++ b/source/libs/sync/src/syncAppendEntriesReply.c
@@ -73,6 +73,7 @@ static void syncNodeStartSnapshotOnce(SSyncNode* ths, SyncIndex beginIndex, Sync
   int32_t        code = ths->pFsm->FpSnapshotStartRead(ths->pFsm, &readerParam, &pReader);
   ASSERT(code == 0);
 
+#if 0
   if (pMsg->privateTerm < pSender->privateTerm) {
     ASSERT(pReader != NULL);
     snapshotSenderStart(pSender, readerParam, snapshot, pReader);
@@ -82,6 +83,7 @@ static void syncNodeStartSnapshotOnce(SSyncNode* ths, SyncIndex beginIndex, Sync
       ths->pFsm->FpSnapshotStopRead(ths->pFsm, pReader);
     }
   }
+#endif
 }
 
 int32_t syncNodeOnAppendEntriesReply(SSyncNode* ths, SyncAppendEntriesReply* pMsg) {
diff --git a/source/libs/sync/src/syncMain.c b/source/libs/sync/src/syncMain.c
index 1ccde7f6b4c79c112bf13df7aa84edec6956a984..eb78ea2894f074d4126b53f0c4b7dcc2eae2059e 100644
--- a/source/libs/sync/src/syncMain.c
+++ b/source/libs/sync/src/syncMain.c
@@ -2236,6 +2236,7 @@ void syncNodeBecomeLeader(SSyncNode* pSyncNode, const char* debugStr) {
   // init peer mgr
   syncNodePeerStateInit(pSyncNode);
 
+#if 0
   // update sender private term
   SSyncSnapshotSender* pMySender = syncNodeGetSnapshotSender(pSyncNode, &(pSyncNode->myRaftId));
   if (pMySender != NULL) {
@@ -2246,6 +2247,7 @@ void syncNodeBecomeLeader(SSyncNode* pSyncNode, const char* debugStr) {
     }
     (pMySender->privateTerm) += 100;
   }
+#endif
 
   // close receiver
   if (snapshotReceiverIsStart(pSyncNode->pNewNodeReceiver)) {
@@ -3561,3 +3563,52 @@ void syncLogRecvLocalCmd(SSyncNode* pSyncNode, const SyncLocalCmd* pMsg, const c
            syncLocalCmdGetStr(pMsg->cmd), pMsg->sdNewTerm, s);
   syncNodeEventLog(pSyncNode, logBuf);
 }
+
+void syncLogSendSyncPreSnapshot(SSyncNode* pSyncNode, const SyncPreSnapshot* pMsg, const char* s) {
+  char     host[64];
+  uint16_t port;
+  syncUtilU642Addr(pMsg->destId.addr, host, sizeof(host), &port);
+  char logBuf[256];
+  snprintf(logBuf, sizeof(logBuf), "send sync-pre-snapshot to %s:%d {term:%" PRIu64 "}, %s", host, port, pMsg->term, s);
+  syncNodeEventLog(pSyncNode, logBuf);
+}
+
+void syncLogRecvSyncPreSnapshot(SSyncNode* pSyncNode, const SyncPreSnapshot* pMsg, const char* s) {
+  char     host[64];
+  uint16_t port;
+  syncUtilU642Addr(pMsg->srcId.addr, host, sizeof(host), &port);
+  char logBuf[256];
+  snprintf(logBuf, sizeof(logBuf), "recv sync-pre-snapshot from %s:%d {term:%" PRIu64 "}, %s", host, port, pMsg->term,
+           s);
+  syncNodeEventLog(pSyncNode, logBuf);
+}
+
+void syncLogSendSyncPreSnapshotReply(SSyncNode* pSyncNode, const SyncPreSnapshotReply* pMsg, const char* s) {
+  char     host[64];
+  uint16_t port;
+  syncUtilU642Addr(pMsg->destId.addr, host, sizeof(host), &port);
+  char logBuf[256];
+  snprintf(logBuf, sizeof(logBuf),
+           "send sync-pre-snapshot-reply to %s:%d {term:%" PRIu64 ", snap-start:%" PRId64 "}, %s", host, port,
+           pMsg->term, pMsg->snapStart, s);
+  syncNodeEventLog(pSyncNode, logBuf);
+}
+
+void syncLogRecvSyncPreSnapshotReply(SSyncNode* pSyncNode, const SyncPreSnapshotReply* pMsg, const char* s) {
+  char     host[64];
+  uint16_t port;
+  syncUtilU642Addr(pMsg->srcId.addr, host, sizeof(host), &port);
+  char logBuf[256];
+  snprintf(logBuf, sizeof(logBuf),
+           "recv sync-pre-snapshot-reply from %s:%d {term:%" PRIu64 ", snap-start:%" PRId64 "}, %s", host, port,
+           pMsg->term, pMsg->snapStart, s);
+  syncNodeEventLog(pSyncNode, logBuf);
+}
+
+void syncLogSendSyncSnapshotSend(SSyncNode* pSyncNode, const SyncSnapshotSend* pMsg, const char* s) {}
+
+void syncLogRecvSyncSnapshotSend(SSyncNode* pSyncNode, const SyncSnapshotSend* pMsg, const char* s) {}
+
+void syncLogSendSyncSnapshotRsp(SSyncNode* pSyncNode, const SyncSnapshotRsp* pMsg, const char* s) {}
+
+void syncLogRecvSyncSnapshotRsp(SSyncNode* pSyncNode, const SyncSnapshotRsp* pMsg, const char* s) {}
diff --git a/source/libs/sync/src/syncMessage.c b/source/libs/sync/src/syncMessage.c
index fa99d3380f2f4e65dd0b03537e229af01f19c9b2..91e8ec91b701890f51eae8c5a5e1502b8a5da25a 100644
--- a/source/libs/sync/src/syncMessage.c
+++ b/source/libs/sync/src/syncMessage.c
@@ -2315,6 +2315,303 @@ void syncHeartbeatReplyLog2(char* s, const SyncHeartbeatReply* pMsg) {
   }
 }
 
+// ---- message process SyncPreSnapshot----
+SyncPreSnapshot* syncPreSnapshotBuild(int32_t vgId) {
+  uint32_t         bytes = sizeof(SyncPreSnapshot);
+  SyncPreSnapshot* pMsg = taosMemoryMalloc(bytes);
+  memset(pMsg, 0, bytes);
+  pMsg->bytes = bytes;
+  pMsg->vgId = vgId;
+  pMsg->msgType = TDMT_SYNC_PRE_SNAPSHOT;
+  return pMsg;
+}
+
+void syncPreSnapshotDestroy(SyncPreSnapshot* pMsg) {
+  if (pMsg != NULL) {
+    taosMemoryFree(pMsg);
+  }
+}
+
+void syncPreSnapshotSerialize(const SyncPreSnapshot* pMsg, char* buf, uint32_t bufLen) {
+  ASSERT(pMsg->bytes <= bufLen);
+  memcpy(buf, pMsg, pMsg->bytes);
+}
+
+void syncPreSnapshotDeserialize(const char* buf, uint32_t len, SyncPreSnapshot* pMsg) {
+  memcpy(pMsg, buf, len);
+  ASSERT(len == pMsg->bytes);
+}
+
+char* syncPreSnapshotSerialize2(const SyncPreSnapshot* pMsg, uint32_t* len) {
+  char* buf = taosMemoryMalloc(pMsg->bytes);
+  ASSERT(buf != NULL);
+  syncPreSnapshotSerialize(pMsg, buf, pMsg->bytes);
+  if (len != NULL) {
+    *len = pMsg->bytes;
+  }
+  return buf;
+}
+
+SyncPreSnapshot* syncPreSnapshotDeserialize2(const char* buf, uint32_t len) {
+  uint32_t         bytes = *((uint32_t*)buf);
+  SyncPreSnapshot* pMsg = taosMemoryMalloc(bytes);
+  ASSERT(pMsg != NULL);
+  syncPreSnapshotDeserialize(buf, len, pMsg);
+  ASSERT(len == pMsg->bytes);
+  return pMsg;
+}
+
+void syncPreSnapshot2RpcMsg(const SyncPreSnapshot* pMsg, SRpcMsg* pRpcMsg) {
+  memset(pRpcMsg, 0, sizeof(*pRpcMsg));
+  pRpcMsg->msgType = pMsg->msgType;
+  pRpcMsg->contLen = pMsg->bytes;
+  pRpcMsg->pCont = rpcMallocCont(pRpcMsg->contLen);
+  syncPreSnapshotSerialize(pMsg, pRpcMsg->pCont, pRpcMsg->contLen);
+}
+
+void syncPreSnapshotFromRpcMsg(const SRpcMsg* pRpcMsg, SyncPreSnapshot* pMsg) {
+  syncPreSnapshotDeserialize(pRpcMsg->pCont, pRpcMsg->contLen, pMsg);
+}
+
+SyncPreSnapshot* syncPreSnapshotFromRpcMsg2(const SRpcMsg* pRpcMsg) {
+  SyncPreSnapshot* pMsg = syncPreSnapshotDeserialize2(pRpcMsg->pCont, pRpcMsg->contLen);
+  ASSERT(pMsg != NULL);
+  return pMsg;
+}
+
+cJSON* syncPreSnapshot2Json(const SyncPreSnapshot* pMsg) {
+  char   u64buf[128] = {0};
+  cJSON* pRoot = cJSON_CreateObject();
+
+  if (pMsg != NULL) {
+    cJSON_AddNumberToObject(pRoot, "bytes", pMsg->bytes);
+    cJSON_AddNumberToObject(pRoot, "vgId", pMsg->vgId);
+    cJSON_AddNumberToObject(pRoot, "msgType", pMsg->msgType);
+
+    cJSON* pSrcId = cJSON_CreateObject();
+    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->srcId.addr);
+    cJSON_AddStringToObject(pSrcId, "addr", u64buf);
+    {
+      uint64_t u64 = pMsg->srcId.addr;
+      cJSON*   pTmp = pSrcId;
+      char     host[128] = {0};
+      uint16_t port;
+      syncUtilU642Addr(u64, host, sizeof(host), &port);
+      cJSON_AddStringToObject(pTmp, "addr_host", host);
+      cJSON_AddNumberToObject(pTmp, "addr_port", port);
+    }
+    cJSON_AddNumberToObject(pSrcId, "vgId", pMsg->srcId.vgId);
+    cJSON_AddItemToObject(pRoot, "srcId", pSrcId);
+
+    cJSON* pDestId = cJSON_CreateObject();
+    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->destId.addr);
+    cJSON_AddStringToObject(pDestId, "addr", u64buf);
+    {
+      uint64_t u64 = pMsg->destId.addr;
+      cJSON*   pTmp = pDestId;
+      char     host[128] = {0};
+      uint16_t port;
+      syncUtilU642Addr(u64, host, sizeof(host), &port);
+      cJSON_AddStringToObject(pTmp, "addr_host", host);
+      cJSON_AddNumberToObject(pTmp, "addr_port", port);
+    }
+    cJSON_AddNumberToObject(pDestId, "vgId", pMsg->destId.vgId);
+    cJSON_AddItemToObject(pRoot, "destId", pDestId);
+
+    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->term);
+    cJSON_AddStringToObject(pRoot, "term", u64buf);
+  }
+
+  cJSON* pJson = cJSON_CreateObject();
+  cJSON_AddItemToObject(pJson, "SyncPreSnapshot", pRoot);
+  return pJson;
+}
+
+char* syncPreSnapshot2Str(const SyncPreSnapshot* pMsg) {
+  cJSON* pJson = syncPreSnapshot2Json(pMsg);
+  char*  serialized = cJSON_Print(pJson);
+  cJSON_Delete(pJson);
+  return serialized;
+}
+
+void syncPreSnapshotPrint(const SyncPreSnapshot* pMsg) {
+  char* serialized = syncPreSnapshot2Str(pMsg);
+  printf("syncPreSnapshotPrint | len:%d | %s \n", (int32_t)strlen(serialized), serialized);
+  fflush(NULL);
+  taosMemoryFree(serialized);
+}
+
+void syncPreSnapshotPrint2(char* s, const SyncPreSnapshot* pMsg) {
+  char* serialized = syncPreSnapshot2Str(pMsg);
+  printf("syncPreSnapshotPrint2 | len:%d | %s | %s \n", (int32_t)strlen(serialized), s, serialized);
+  fflush(NULL);
+  taosMemoryFree(serialized);
+}
+
+void syncPreSnapshotLog(const SyncPreSnapshot* pMsg) {
+  char* serialized = syncPreSnapshot2Str(pMsg);
+  sTrace("syncPreSnapshotLog | len:%d | %s", (int32_t)strlen(serialized), serialized);
+  taosMemoryFree(serialized);
+}
+
+void syncPreSnapshotLog2(char* s, const SyncPreSnapshot* pMsg) {
+  if (gRaftDetailLog) {
+    char* serialized = syncPreSnapshot2Str(pMsg);
+    sTrace("syncPreSnapshotLog2 | len:%d | %s | %s", (int32_t)strlen(serialized), s, serialized);
+    taosMemoryFree(serialized);
+  }
+}
+
+// ---- message process SyncPreSnapshotReply----
+SyncPreSnapshotReply* syncPreSnapshotReplyBuild(int32_t vgId) {
+  uint32_t              bytes = sizeof(SyncPreSnapshotReply);
+  SyncPreSnapshotReply* pMsg = taosMemoryMalloc(bytes);
+  memset(pMsg, 0, bytes);
+  pMsg->bytes = bytes;
+  pMsg->vgId = vgId;
+  pMsg->msgType = TDMT_SYNC_PRE_SNAPSHOT_REPLY;
+  return pMsg;
+}
+
+void syncPreSnapshotReplyDestroy(SyncPreSnapshotReply* pMsg) {
+  if (pMsg != NULL) {
+    taosMemoryFree(pMsg);
+  }
+}
+
+void syncPreSnapshotReplySerialize(const SyncPreSnapshotReply* pMsg, char* buf, uint32_t bufLen) {
+  ASSERT(pMsg->bytes <= bufLen);
+  memcpy(buf, pMsg, pMsg->bytes);
+}
+
+void syncPreSnapshotReplyDeserialize(const char* buf, uint32_t len, SyncPreSnapshotReply* pMsg) {
+  memcpy(pMsg, buf, len);
+  ASSERT(len == pMsg->bytes);
+}
+
+char* syncPreSnapshotReplySerialize2(const SyncPreSnapshotReply* pMsg, uint32_t* len) {
+  char* buf = taosMemoryMalloc(pMsg->bytes);
+  ASSERT(buf != NULL);
+  syncPreSnapshotReplySerialize(pMsg, buf, pMsg->bytes);
+  if (len != NULL) {
+    *len = pMsg->bytes;
+  }
+  return buf;
+}
+
+SyncPreSnapshotReply* syncPreSnapshotReplyDeserialize2(const char* buf, uint32_t len) {
+  uint32_t              bytes = *((uint32_t*)buf);
+  SyncPreSnapshotReply* pMsg = taosMemoryMalloc(bytes);
+  ASSERT(pMsg != NULL);
+  syncPreSnapshotReplyDeserialize(buf, len, pMsg);
+  ASSERT(len == pMsg->bytes);
+  return pMsg;
+}
+
+void syncPreSnapshotReply2RpcMsg(const SyncPreSnapshotReply* pMsg, SRpcMsg* pRpcMsg) {
+  memset(pRpcMsg, 0, sizeof(*pRpcMsg));
+  pRpcMsg->msgType = pMsg->msgType;
+  pRpcMsg->contLen = pMsg->bytes;
+  pRpcMsg->pCont = rpcMallocCont(pRpcMsg->contLen);
+  syncPreSnapshotReplySerialize(pMsg, pRpcMsg->pCont, pRpcMsg->contLen);
+}
+
+void syncPreSnapshotReplyFromRpcMsg(const SRpcMsg* pRpcMsg, SyncPreSnapshotReply* pMsg) {
+  syncPreSnapshotReplyDeserialize(pRpcMsg->pCont, pRpcMsg->contLen, pMsg);
+}
+
+SyncPreSnapshotReply* syncPreSnapshotReplyFromRpcMsg2(const SRpcMsg* pRpcMsg) {
+  SyncPreSnapshotReply* pMsg = syncPreSnapshotReplyDeserialize2(pRpcMsg->pCont, pRpcMsg->contLen);
+  ASSERT(pMsg != NULL);
+  return pMsg;
+}
+
+cJSON* syncPreSnapshotReply2Json(const SyncPreSnapshotReply* pMsg) {
+  char   u64buf[128] = {0};
+  cJSON* pRoot = cJSON_CreateObject();
+
+  if (pMsg != NULL) {
+    cJSON_AddNumberToObject(pRoot, "bytes", pMsg->bytes);
+    cJSON_AddNumberToObject(pRoot, "vgId", pMsg->vgId);
+    cJSON_AddNumberToObject(pRoot, "msgType", pMsg->msgType);
+
+    cJSON* pSrcId = cJSON_CreateObject();
+    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->srcId.addr);
+    cJSON_AddStringToObject(pSrcId, "addr", u64buf);
+    {
+      uint64_t u64 = pMsg->srcId.addr;
+      cJSON*   pTmp = pSrcId;
+      char     host[128] = {0};
+      uint16_t port;
+      syncUtilU642Addr(u64, host, sizeof(host), &port);
+      cJSON_AddStringToObject(pTmp, "addr_host", host);
+      cJSON_AddNumberToObject(pTmp, "addr_port", port);
+    }
+    cJSON_AddNumberToObject(pSrcId, "vgId", pMsg->srcId.vgId);
+    cJSON_AddItemToObject(pRoot, "srcId", pSrcId);
+
+    cJSON* pDestId = cJSON_CreateObject();
+    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->destId.addr);
+    cJSON_AddStringToObject(pDestId, "addr", u64buf);
+    {
+      uint64_t u64 = pMsg->destId.addr;
+      cJSON*   pTmp = pDestId;
+      char     host[128] = {0};
+      uint16_t port;
+      syncUtilU642Addr(u64, host, sizeof(host), &port);
+      cJSON_AddStringToObject(pTmp, "addr_host", host);
+      cJSON_AddNumberToObject(pTmp, "addr_port", port);
+    }
+    cJSON_AddNumberToObject(pDestId, "vgId", pMsg->destId.vgId);
+    cJSON_AddItemToObject(pRoot, "destId", pDestId);
+
+    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->term);
+    cJSON_AddStringToObject(pRoot, "term", u64buf);
+
+    snprintf(u64buf, sizeof(u64buf), "%" PRId64, pMsg->snapStart);
+    cJSON_AddStringToObject(pRoot, "snap-start", u64buf);
+  }
+
+  cJSON* pJson = cJSON_CreateObject();
+  cJSON_AddItemToObject(pJson, "SyncPreSnapshotReply", pRoot);
+  return pJson;
+}
+
+char* syncPreSnapshotReply2Str(const SyncPreSnapshotReply* pMsg) {
+  cJSON* pJson = syncPreSnapshotReply2Json(pMsg);
+  char*  serialized = cJSON_Print(pJson);
+  cJSON_Delete(pJson);
+  return serialized;
+}
+
+void syncPreSnapshotReplyPrint(const SyncPreSnapshotReply* pMsg) {
+  char* serialized = syncPreSnapshotReply2Str(pMsg);
+  printf("syncPreSnapshotReplyPrint | len:%d | %s \n", (int32_t)strlen(serialized), serialized);
+  fflush(NULL);
+  taosMemoryFree(serialized);
+}
+
+void syncPreSnapshotReplyPrint2(char* s, const SyncPreSnapshotReply* pMsg) {
+  char* serialized = syncPreSnapshotReply2Str(pMsg);
+  printf("syncPreSnapshotReplyPrint2 | len:%d | %s | %s \n", (int32_t)strlen(serialized), s, serialized);
+  fflush(NULL);
+  taosMemoryFree(serialized);
+}
+
+void syncPreSnapshotReplyLog(const SyncPreSnapshotReply* pMsg) {
+  char* serialized = syncPreSnapshotReply2Str(pMsg);
+  sTrace("syncPreSnapshotReplyLog | len:%d | %s", (int32_t)strlen(serialized), serialized);
+  taosMemoryFree(serialized);
+}
+
+void syncPreSnapshotReplyLog2(char* s, const SyncPreSnapshotReply* pMsg) {
+  if (gRaftDetailLog) {
+    char* serialized = syncPreSnapshotReply2Str(pMsg);
+    sTrace("syncPreSnapshotReplyLog2 | len:%d | %s | %s", (int32_t)strlen(serialized), s, serialized);
+    taosMemoryFree(serialized);
+  }
+}
+
 // ---- message process SyncApplyMsg----
 SyncApplyMsg* syncApplyMsgBuild(uint32_t dataLen) {
   uint32_t      bytes = sizeof(SyncApplyMsg) + dataLen;
@@ -2576,8 +2873,8 @@ cJSON* syncSnapshotSend2Json(const SyncSnapshotSend* pMsg) {
     snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->term);
     cJSON_AddStringToObject(pRoot, "term", u64buf);
 
-    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->privateTerm);
-    cJSON_AddStringToObject(pRoot, "privateTerm", u64buf);
+    snprintf(u64buf, sizeof(u64buf), "%" PRId64, pMsg->startTime);
+    cJSON_AddStringToObject(pRoot, "startTime", u64buf);
 
     snprintf(u64buf, sizeof(u64buf), "%" PRId64, pMsg->beginIndex);
     cJSON_AddStringToObject(pRoot, "beginIndex", u64buf);
@@ -2751,8 +3048,8 @@ cJSON* syncSnapshotRsp2Json(const SyncSnapshotRsp* pMsg) {
     snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->term);
     cJSON_AddStringToObject(pRoot, "term", u64buf);
 
-    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pMsg->privateTerm);
-    cJSON_AddStringToObject(pRoot, "privateTerm", u64buf);
+    snprintf(u64buf, sizeof(u64buf), "%" PRId64, pMsg->startTime);
+    cJSON_AddStringToObject(pRoot, "startTime", u64buf);
 
     snprintf(u64buf, sizeof(u64buf), "%" PRId64, pMsg->lastIndex);
     cJSON_AddStringToObject(pRoot, "lastIndex", u64buf);
@@ -2762,6 +3059,9 @@ cJSON* syncSnapshotRsp2Json(const SyncSnapshotRsp* pMsg) {
 
     cJSON_AddNumberToObject(pRoot, "ack", pMsg->ack);
     cJSON_AddNumberToObject(pRoot, "code", pMsg->code);
+
+    snprintf(u64buf, sizeof(u64buf), "%" PRId64, pMsg->snapBeginIndex);
+    cJSON_AddStringToObject(pRoot, "snap-begin", u64buf);
   }
 
   cJSON* pJson = cJSON_CreateObject();
diff --git a/source/libs/sync/src/syncReplication.c b/source/libs/sync/src/syncReplication.c
index af531234213286acccb986e5ff056ee868a65a0e..4aa8b0bc34adca78cd1aa76fd0b33fde763b8505 100644
--- a/source/libs/sync/src/syncReplication.c
+++ b/source/libs/sync/src/syncReplication.c
@@ -62,8 +62,8 @@ int32_t syncNodeReplicateOne(SSyncNode* pSyncNode, SRaftId* pDestId) {
     syncNodeEventLog(pSyncNode, logBuf);
 
     // start snapshot
-    int32_t code = syncNodeStartSnapshot(pSyncNode, pDestId);
-    ASSERT(code == 0);
+    // int32_t code = syncNodeStartSnapshot(pSyncNode, pDestId);
+
     return 0;
   }
 
diff --git a/source/libs/sync/src/syncSnapshot.c b/source/libs/sync/src/syncSnapshot.c
index a7bafa9f28f2b6bdeeb568477cc524648d67cd05..b7283157462f8860156571b0bbdb22cfdc2e4c51 100644
--- a/source/libs/sync/src/syncSnapshot.c
+++ b/source/libs/sync/src/syncSnapshot.c
@@ -41,8 +41,6 @@ SSyncSnapshotSender *snapshotSenderCreate(SSyncNode *pSyncNode, int32_t replicaI
     }
     memset(pSender, 0, sizeof(*pSender));
 
-    int64_t timeNow = taosGetTimestampMs();
-
     pSender->start = false;
     pSender->seq = SYNC_SNAPSHOT_SEQ_INVALID;
     pSender->ack = SYNC_SNAPSHOT_SEQ_INVALID;
@@ -53,8 +51,7 @@ SSyncSnapshotSender *snapshotSenderCreate(SSyncNode *pSyncNode, int32_t replicaI
     pSender->pSyncNode = pSyncNode;
     pSender->replicaIndex = replicaIndex;
     pSender->term = pSyncNode->pRaftStore->currentTerm;
-    pSender->privateTerm = timeNow + 100;
-    pSender->startTime = timeNow;
+    pSender->startTime = 0;
     pSender->pSyncNode->pFsm->FpGetSnapshotInfo(pSender->pSyncNode->pFsm, &(pSender->snapshot));
     pSender->finish = false;
   } else {
@@ -88,88 +85,30 @@ void snapshotSenderDestroy(SSyncSnapshotSender *pSender) {
 
 bool snapshotSenderIsStart(SSyncSnapshotSender *pSender) { return pSender->start; }
 
-// begin send snapshot by param, snapshot, pReader
-//
-// action:
-// 1. assert reader not start
-// 2. update state
-// 3. send first snapshot block
-int32_t snapshotSenderStart(SSyncSnapshotSender *pSender, SSnapshotParam snapshotParam, SSnapshot snapshot,
-                            void *pReader) {
+int32_t snapshotSenderStart(SSyncSnapshotSender *pSender) {
   ASSERT(!snapshotSenderIsStart(pSender));
 
-  // init snapshot, parm, reader
-  ASSERT(pSender->pReader == NULL);
-  pSender->pReader = pReader;
-  pSender->snapshot = snapshot;
-  pSender->snapshotParam = snapshotParam;
-
-  // init current block
-  if (pSender->pCurrentBlock != NULL) {
-    taosMemoryFree(pSender->pCurrentBlock);
-  }
-  pSender->blockLen = 0;
-
-  // update term
-  pSender->term = pSender->pSyncNode->pRaftStore->currentTerm;
-  ++(pSender->privateTerm);  // increase private term
-
-  // update state
-  pSender->finish = false;
   pSender->start = true;
   pSender->seq = SYNC_SNAPSHOT_SEQ_BEGIN;
   pSender->ack = SYNC_SNAPSHOT_SEQ_INVALID;
+  pSender->pReader = NULL;
+  pSender->pCurrentBlock = NULL;
+  pSender->blockLen = 0;
 
-  // init last config
-  if (pSender->snapshot.lastConfigIndex != SYNC_INDEX_INVALID) {
-    int32_t         code = 0;
-    SSyncRaftEntry *pEntry = NULL;
-    bool            getLastConfig = false;
-
-    code = pSender->pSyncNode->pLogStore->syncLogGetEntry(pSender->pSyncNode->pLogStore,
-                                                          pSender->snapshot.lastConfigIndex, &pEntry);
-    if (code == 0 && pEntry != NULL) {
-      SRpcMsg rpcMsg;
-      syncEntry2OriginalRpc(pEntry, &rpcMsg);
-
-      SSyncCfg lastConfig;
-      int32_t  ret = syncCfgFromStr(rpcMsg.pCont, &lastConfig);
-      ASSERT(ret == 0);
-      pSender->lastConfig = lastConfig;
-      getLastConfig = true;
-
-      rpcFreeCont(rpcMsg.pCont);
-      syncEntryDestory(pEntry);
-    } else {
-      if (pSender->snapshot.lastConfigIndex == pSender->pSyncNode->pRaftCfg->lastConfigIndex) {
-        sTrace("vgId:%d, sync sender get cfg from local", pSender->pSyncNode->vgId);
-        pSender->lastConfig = pSender->pSyncNode->pRaftCfg->cfg;
-        getLastConfig = true;
-      }
-    }
+  pSender->snapshotParam.start = SYNC_INDEX_INVALID;
+  pSender->snapshotParam.end = SYNC_INDEX_INVALID;
 
-    // last config not found in wal, update to -1
-    if (!getLastConfig) {
-      SyncIndex oldLastConfigIndex = pSender->snapshot.lastConfigIndex;
-      SyncIndex newLastConfigIndex = SYNC_INDEX_INVALID;
-      pSender->snapshot.lastConfigIndex = SYNC_INDEX_INVALID;
-      memset(&(pSender->lastConfig), 0, sizeof(SSyncCfg));
+  pSender->snapshot.data = NULL;
+  pSender->snapshotParam.end = SYNC_INDEX_INVALID;
+  pSender->snapshot.lastApplyIndex = SYNC_INDEX_INVALID;
+  pSender->snapshot.lastApplyTerm = SYNC_TERM_INVALID;
+  pSender->snapshot.lastConfigIndex = SYNC_INDEX_INVALID;
 
-      // event log
-      do {
-        char logBuf[128];
-        snprintf(logBuf, sizeof(logBuf), "snapshot sender update lcindex from %" PRId64 " to %" PRId64,
-                 oldLastConfigIndex, newLastConfigIndex);
-        char *eventLog = snapshotSender2SimpleStr(pSender, logBuf);
-        syncNodeEventLog(pSender->pSyncNode, eventLog);
-        taosMemoryFree(eventLog);
-      } while (0);
-    }
-
-  } else {
-    // no last config
-    memset(&(pSender->lastConfig), 0, sizeof(SSyncCfg));
-  }
+  memset(&(pSender->lastConfig), 0, sizeof(pSender->lastConfig));
+  pSender->sendingMS = 0;
+  pSender->term = pSender->pSyncNode->pRaftStore->currentTerm;
+  pSender->startTime = taosGetTimestampMs();
+  pSender->finish = false;
 
   // build begin msg
   SyncSnapshotSend *pMsg = syncSnapshotSendBuild(0, pSender->pSyncNode->vgId);
@@ -181,8 +120,8 @@ int32_t snapshotSenderStart(SSyncSnapshotSender *pSender, SSnapshotParam snapsho
   pMsg->lastTerm = pSender->snapshot.lastApplyTerm;
   pMsg->lastConfigIndex = pSender->snapshot.lastConfigIndex;
   pMsg->lastConfig = pSender->lastConfig;
-  pMsg->seq = pSender->seq;  // SYNC_SNAPSHOT_SEQ_BEGIN
-  pMsg->privateTerm = pSender->privateTerm;
+  pMsg->startTime = pSender->startTime;
+  pMsg->seq = SYNC_SNAPSHOT_SEQ_PRE_SNAPSHOT;
 
   // send msg
   SRpcMsg rpcMsg;
@@ -201,6 +140,10 @@ int32_t snapshotSenderStart(SSyncSnapshotSender *pSender, SSnapshotParam snapsho
 }
 
 int32_t snapshotSenderStop(SSyncSnapshotSender *pSender, bool finish) {
+  // update flag
+  pSender->start = false;
+  pSender->finish = finish;
+
   // close reader
   if (pSender->pReader != NULL) {
     int32_t ret = pSender->pSyncNode->pFsm->FpSnapshotStopRead(pSender->pSyncNode->pFsm, pSender->pReader);
@@ -215,12 +158,6 @@ int32_t snapshotSenderStop(SSyncSnapshotSender *pSender, bool finish) {
     pSender->blockLen = 0;
   }
 
-  // update flag
-  pSender->start = false;
-  pSender->finish = finish;
-
-  // do not update term, maybe print
-
   // event log
   do {
     char *eventLog = snapshotSender2SimpleStr(pSender, "snapshot sender stop");
@@ -263,7 +200,9 @@ int32_t snapshotSend(SSyncSnapshotSender *pSender) {
   pMsg->lastConfigIndex = pSender->snapshot.lastConfigIndex;
   pMsg->lastConfig = pSender->lastConfig;
   pMsg->seq = pSender->seq;
-  pMsg->privateTerm = pSender->privateTerm;
+
+  // pMsg->privateTerm = pSender->privateTerm;
+
   memcpy(pMsg->data, pSender->pCurrentBlock, pSender->blockLen);
 
   // send msg
@@ -302,7 +241,9 @@ int32_t snapshotReSend(SSyncSnapshotSender *pSender) {
     pMsg->lastConfigIndex = pSender->snapshot.lastConfigIndex;
     pMsg->lastConfig = pSender->lastConfig;
     pMsg->seq = pSender->seq;
-    pMsg->privateTerm = pSender->privateTerm;
+
+    //  pMsg->privateTerm = pSender->privateTerm;
+
     memcpy(pMsg->data, pSender->pCurrentBlock, pSender->blockLen);
 
     // send msg
@@ -367,8 +308,10 @@ cJSON *snapshotSender2Json(SSyncSnapshotSender *pSender) {
     cJSON_AddNumberToObject(pRoot, "replicaIndex", pSender->replicaIndex);
     snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pSender->term);
     cJSON_AddStringToObject(pRoot, "term", u64buf);
-    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pSender->privateTerm);
-    cJSON_AddStringToObject(pRoot, "privateTerm", u64buf);
+
+    //  snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pSender->privateTerm);
+    //  cJSON_AddStringToObject(pRoot, "privateTerm", u64buf);
+
     cJSON_AddNumberToObject(pRoot, "finish", pSender->finish);
   }
 
@@ -395,30 +338,38 @@ char *snapshotSender2SimpleStr(SSyncSnapshotSender *pSender, char *event) {
 
   snprintf(s, len,
            "%s {%p s-param:%" PRId64 " e-param:%" PRId64 " laindex:%" PRId64 " laterm:%" PRIu64 " lcindex:%" PRId64
-           " seq:%d ack:%d finish:%d pterm:%" PRIu64
-           " "
-           "replica-index:%d %s:%d}",
+           " seq:%d ack:%d finish:%d replica-index:%d %s:%d}",
            event, pSender, pSender->snapshotParam.start, pSender->snapshotParam.end, pSender->snapshot.lastApplyIndex,
            pSender->snapshot.lastApplyTerm, pSender->snapshot.lastConfigIndex, pSender->seq, pSender->ack,
-           pSender->finish, pSender->privateTerm, pSender->replicaIndex, host, port);
+           pSender->finish, pSender->replicaIndex, host, port);
 
   return s;
 }
 
 int32_t syncNodeStartSnapshot(SSyncNode *pSyncNode, SRaftId *pDestId) {
-  // calculate <start, end> index
-
-  syncNodeEventLog(pSyncNode, "start snapshot ...");
+  syncNodeEventLog(pSyncNode, "starting snapshot ...");
 
   SSyncSnapshotSender *pSender = syncNodeGetSnapshotSender(pSyncNode, pDestId);
   if (pSender == NULL) {
-    // create sender
-  } else {
-    // if <start, end> is same
-    // return 0;
+    syncNodeErrorLog(pSyncNode, "start snapshot error, sender is null");
+    return -1;
+  }
+
+  int32_t code = 0;
+
+  if (snapshotSenderIsStart(pSender)) {
+    code = snapshotSenderStop(pSender, false);
+    if (code != 0) {
+      syncNodeErrorLog(pSyncNode, "snapshot sender stop error");
+      return -1;
+    }
   }
 
-  // send begin msg
+  code = snapshotSenderStart(pSender);
+  if (code != 0) {
+    syncNodeErrorLog(pSyncNode, "snapshot sender start error");
+    return -1;
+  }
 
   return 0;
 }
@@ -440,7 +391,6 @@ SSyncSnapshotReceiver *snapshotReceiverCreate(SSyncNode *pSyncNode, SRaftId from
     pReceiver->pSyncNode = pSyncNode;
     pReceiver->fromId = fromId;
     pReceiver->term = pSyncNode->pRaftStore->currentTerm;
-    pReceiver->privateTerm = 0;
     pReceiver->snapshot.data = NULL;
     pReceiver->snapshot.lastApplyIndex = SYNC_INDEX_INVALID;
     pReceiver->snapshot.lastApplyTerm = 0;
@@ -474,25 +424,27 @@ bool snapshotReceiverIsStart(SSyncSnapshotReceiver *pReceiver) { return pReceive
 // receive first snapshot data
 // write first block data
 static void snapshotReceiverDoStart(SSyncSnapshotReceiver *pReceiver, SyncSnapshotSend *pBeginMsg) {
-  // update state
-  pReceiver->term = pReceiver->pSyncNode->pRaftStore->currentTerm;
-  pReceiver->privateTerm = pBeginMsg->privateTerm;
+  pReceiver->start = true;
   pReceiver->ack = SYNC_SNAPSHOT_SEQ_BEGIN;
+
+  // start writer
+  ASSERT(pReceiver->pWriter == NULL);
+  int32_t ret = pReceiver->pSyncNode->pFsm->FpSnapshotStartWrite(pReceiver->pSyncNode->pFsm,
+                                                                 &(pReceiver->snapshotParam), &(pReceiver->pWriter));
+  ASSERT(ret == 0);
+
+  pReceiver->term = pReceiver->pSyncNode->pRaftStore->currentTerm;
+  pReceiver->snapshotParam.start = pBeginMsg->beginIndex;
+  pReceiver->snapshotParam.end = pBeginMsg->lastIndex;
+
   pReceiver->fromId = pBeginMsg->srcId;
-  pReceiver->start = true;
 
   // update snapshot
   pReceiver->snapshot.lastApplyIndex = pBeginMsg->lastIndex;
   pReceiver->snapshot.lastApplyTerm = pBeginMsg->lastTerm;
   pReceiver->snapshot.lastConfigIndex = pBeginMsg->lastConfigIndex;
-  pReceiver->snapshotParam.start = pBeginMsg->beginIndex;
-  pReceiver->snapshotParam.end = pBeginMsg->lastIndex;
 
-  // start writer
-  ASSERT(pReceiver->pWriter == NULL);
-  int32_t ret = pReceiver->pSyncNode->pFsm->FpSnapshotStartWrite(pReceiver->pSyncNode->pFsm,
-                                                                 &(pReceiver->snapshotParam), &(pReceiver->pWriter));
-  ASSERT(ret == 0);
+  pReceiver->startTime = pBeginMsg->startTime;
 
   // event log
   do {
@@ -523,22 +475,9 @@ void snapshotReceiverForceStop(SSyncSnapshotReceiver *pReceiver) {
 }
 
 // if receiver receive msg from seq = SYNC_SNAPSHOT_SEQ_BEGIN, start receiver
-// if already start, force close, start again
 int32_t snapshotReceiverStart(SSyncSnapshotReceiver *pReceiver, SyncSnapshotSend *pBeginMsg) {
-  if (!snapshotReceiverIsStart(pReceiver)) {
-    // first start
-    snapshotReceiverDoStart(pReceiver, pBeginMsg);
-
-  } else {
-    // already start
-    sInfo("vgId:%d, snapshot recv, receiver already start", pReceiver->pSyncNode->vgId);
-
-    // force close, abandon incomplete data
-    snapshotReceiverForceStop(pReceiver);
-
-    // start again
-    snapshotReceiverDoStart(pReceiver, pBeginMsg);
-  }
+  ASSERT(!snapshotReceiverIsStart(pReceiver));
+  snapshotReceiverDoStart(pReceiver, pBeginMsg);
 
   return 0;
 }
@@ -698,8 +637,8 @@ cJSON *snapshotReceiver2Json(SSyncSnapshotReceiver *pReceiver) {
     snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pReceiver->term);
     cJSON_AddStringToObject(pRoot, "term", u64buf);
 
-    snprintf(u64buf, sizeof(u64buf), "%" PRIu64, pReceiver->privateTerm);
-    cJSON_AddStringToObject(pRoot, "privateTerm", u64buf);
+    snprintf(u64buf, sizeof(u64buf), "%" PRId64, pReceiver->startTime);
+    cJSON_AddStringToObject(pRoot, "startTime", u64buf);
   }
 
   cJSON *pJson = cJSON_CreateObject();
@@ -724,38 +663,204 @@ char *snapshotReceiver2SimpleStr(SSyncSnapshotReceiver *pReceiver, char *event)
   syncUtilU642Addr(fromId.addr, host, sizeof(host), &port);
 
   snprintf(s, len,
-           "%s {%p start:%d ack:%d term:%" PRIu64 " pterm:%" PRIu64 " from:%s:%d s-param:%" PRId64 " e-param:%" PRId64
-           " laindex:%" PRId64 " laterm:%" PRIu64
+           "%s {%p start:%d ack:%d term:%" PRIu64 " start-time:%" PRId64 " from:%s:%d s-param:%" PRId64
+           " e-param:%" PRId64 " laindex:%" PRId64 " laterm:%" PRIu64
            " "
            "lcindex:%" PRId64 "}",
-           event, pReceiver, pReceiver->start, pReceiver->ack, pReceiver->term, pReceiver->privateTerm, host, port,
+           event, pReceiver, pReceiver->start, pReceiver->ack, pReceiver->term, pReceiver->startTime, host, port,
            pReceiver->snapshotParam.start, pReceiver->snapshotParam.end, pReceiver->snapshot.lastApplyIndex,
            pReceiver->snapshot.lastApplyTerm, pReceiver->snapshot.lastConfigIndex);
 
   return s;
 }
 
+SyncIndex syncNodeGetSnapBeginIndex(SSyncNode *ths) {
+  SyncIndex snapStart = SYNC_INDEX_INVALID;
+
+  if (syncNodeIsMnode(ths)) {
+    snapStart = SYNC_INDEX_BEGIN;
+
+  } else {
+    SSyncLogStoreData *pData = ths->pLogStore->data;
+    SWal              *pWal = pData->pWal;
+
+    bool    isEmpty = ths->pLogStore->syncLogIsEmpty(ths->pLogStore);
+    int64_t walCommitVer = walGetCommittedVer(pWal);
+
+    if (!isEmpty && ths->commitIndex != walCommitVer) {
+      char logBuf[128];
+      snprintf(logBuf, sizeof(logBuf), "commit not same, wal-commit:%" PRId64 ", commit:%" PRId64 ", ignore",
+               walCommitVer, ths->commitIndex);
+      syncNodeErrorLog(ths, logBuf);
+
+      snapStart = walCommitVer + 1;
+    } else {
+      snapStart = ths->commitIndex + 1;
+    }
+  }
+
+  return snapStart;
+}
+
+static int32_t syncNodeOnSnapshotPre(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
+  SSyncSnapshotReceiver *pReceiver = pSyncNode->pNewNodeReceiver;
+
+  if (snapshotReceiverIsStart(pReceiver)) {
+    // already start
+
+    if (pMsg->startTime > pReceiver->startTime) {
+      goto _START_RECEIVER;
+
+    } else if (pMsg->startTime == pReceiver->startTime) {
+      goto _SEND_REPLY;
+
+    } else {
+      // ignore
+      return 0;
+    }
+
+  } else {
+    // start new
+    goto _START_RECEIVER;
+  }
+
+_START_RECEIVER:
+  if (taosGetTimestampMs() - pMsg->startTime > SNAPSHOT_MAX_CLOCK_SKEW_MS) {
+    syncNodeErrorLog(pSyncNode, "snapshot receiver time skew too much");
+    return -1;
+  } else {
+    // waiting for clock match
+    while (taosGetTimestampMs() > pMsg->startTime) {
+      taosMsleep(10);
+    }
+
+    snapshotReceiverStart(pReceiver, pMsg);  // set start-time same with sender
+  }
+
+_SEND_REPLY:
+    // build msg
+    ;  // make complier happy
+  SyncSnapshotRsp *pRspMsg = syncSnapshotRspBuild(pSyncNode->vgId);
+  pRspMsg->srcId = pSyncNode->myRaftId;
+  pRspMsg->destId = pMsg->srcId;
+  pRspMsg->term = pSyncNode->pRaftStore->currentTerm;
+  pRspMsg->lastIndex = pMsg->lastIndex;
+  pRspMsg->lastTerm = pMsg->lastTerm;
+  pRspMsg->startTime = pReceiver->startTime;
+  pRspMsg->ack = pMsg->seq;  // receiver maybe already closed
+  pRspMsg->code = 0;
+  pRspMsg->snapBeginIndex = syncNodeGetSnapBeginIndex(pSyncNode);
+
+  // send msg
+  SRpcMsg rpcMsg;
+  syncSnapshotRsp2RpcMsg(pRspMsg, &rpcMsg);
+  syncNodeSendMsgById(&(pRspMsg->destId), pSyncNode, &rpcMsg);
+  syncSnapshotRspDestroy(pRspMsg);
+
+  return 0;
+}
+
+static int32_t syncNodeOnSnapshotBegin(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
+  // condition 1
+  SSyncSnapshotReceiver *pReceiver = pSyncNode->pNewNodeReceiver;
+
+  if (snapshotReceiverIsStart(pReceiver)) {
+    if (pMsg->startTime > pReceiver->startTime) {
+      snapshotReceiverStop(pReceiver);
+
+    } else if (pMsg->startTime == pReceiver->startTime) {
+      return 0;
+    } else {
+      // ignore
+      syncNodeEventLog(pSyncNode, "msg ignore");
+      return 0;
+    }
+  }
+
+_START_RECEIVER:
+  if (taosGetTimestampMs() - pMsg->startTime > SNAPSHOT_MAX_CLOCK_SKEW_MS) {
+    syncNodeErrorLog(pSyncNode, "snapshot receiver time skew too much");
+    return -1;
+  } else {
+    // waiting for clock match
+    while (taosGetTimestampMs() > pMsg->startTime) {
+      taosMsleep(10);
+    }
+
+    snapshotReceiverStart(pReceiver, pMsg);
+
+    // build msg
+    SyncSnapshotRsp *pRspMsg = syncSnapshotRspBuild(pSyncNode->vgId);
+    pRspMsg->srcId = pSyncNode->myRaftId;
+    pRspMsg->destId = pMsg->srcId;
+    pRspMsg->term = pSyncNode->pRaftStore->currentTerm;
+    pRspMsg->lastIndex = pMsg->lastIndex;
+    pRspMsg->lastTerm = pMsg->lastTerm;
+    pRspMsg->ack = pReceiver->ack;  // receiver maybe already closed
+    pRspMsg->code = 0;
+
+    // send msg
+    SRpcMsg rpcMsg;
+    syncSnapshotRsp2RpcMsg(pRspMsg, &rpcMsg);
+    syncNodeSendMsgById(&(pRspMsg->destId), pSyncNode, &rpcMsg);
+    syncSnapshotRspDestroy(pRspMsg);
+  }
+
+  return 0;
+}
+
+static int32_t syncNodeOnSnapshotTransfer(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) { return 0; }
+
+static int32_t syncNodeOnSnapshotEnd(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) { return 0; }
+
 // receiver on message
 //
-// condition 1, recv SYNC_SNAPSHOT_SEQ_BEGIN, start receiver, update privateTerm
-// condition 2, recv SYNC_SNAPSHOT_SEQ_END, finish receiver(apply snapshot data, update commit index, maybe reconfig)
-// condition 3, recv SYNC_SNAPSHOT_SEQ_FORCE_CLOSE, force close
-// condition 4, got data, update ack
+// condition 1, recv SYNC_SNAPSHOT_SEQ_PRE_SNAPSHOT
+//              if receiver already start
+//                    if sender.start-time > receiver.start-time, restart receiver(reply snapshot start)
+//                    if sender.start-time = receiver.start-time, maybe duplicate msg
+//                    if sender.start-time < receiver.start-time, ignore
+//              else
+//                    waiting for clock match
+//                    start receiver(reply snapshot start)
+//
+// condition 2, recv SYNC_SNAPSHOT_SEQ_BEGIN
+//              a. create writer with <begin, end>
+//
+// condition 3, recv SYNC_SNAPSHOT_SEQ_END, finish receiver(apply snapshot data, update commit index, maybe reconfig)
+//
+// condition 4, recv SYNC_SNAPSHOT_SEQ_FORCE_CLOSE, force close
+//
+// condition 5, got data, update ack
 //
 int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
-  // get receiver
-  SSyncSnapshotReceiver *pReceiver = pSyncNode->pNewNodeReceiver;
-  bool                   needRsp = false;
+  // if already drop replica, do not process
+  if (!syncNodeInRaftGroup(pSyncNode, &(pMsg->srcId))) {
+    syncLogRecvSyncSnapshotSend(pSyncNode, pMsg, "not in my config");
+    return 0;
+  }
+
+  if (pMsg->term < pSyncNode->pRaftStore->currentTerm) {
+    syncLogRecvSyncSnapshotSend(pSyncNode, pMsg, "reject, small term");
+    return 0;
+  }
+
+  if (pMsg->term > pSyncNode->pRaftStore->currentTerm) {
+    syncNodeStepDown(pSyncNode, pMsg->term);
+  }
+  syncNodeResetElectTimer(pSyncNode);
+
   int32_t                code = 0;
+  SSyncSnapshotReceiver *pReceiver = pSyncNode->pNewNodeReceiver;
 
   // state, term, seq/ack
   if (pSyncNode->state == TAOS_SYNC_STATE_FOLLOWER) {
     if (pMsg->term == pSyncNode->pRaftStore->currentTerm) {
-      if (pMsg->seq == SYNC_SNAPSHOT_SEQ_BEGIN) {
-        // condition 1
-        // begin, no data
-        snapshotReceiverStart(pReceiver, pMsg);
-        needRsp = true;
+      if (pMsg->seq == SYNC_SNAPSHOT_SEQ_PRE_SNAPSHOT) {
+        syncNodeOnSnapshotPre(pSyncNode, pMsg);
+
+      } else if (pMsg->seq == SYNC_SNAPSHOT_SEQ_BEGIN) {
+        syncNodeOnSnapshotBegin(pSyncNode, pMsg);
 
       } else if (pMsg->seq == SYNC_SNAPSHOT_SEQ_END) {
         // condition 2
@@ -764,7 +869,7 @@ int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
         if (code == 0) {
           snapshotReceiverStop(pReceiver);
         }
-        needRsp = true;
+        bool needRsp = true;
 
         // maybe update lastconfig
         if (pMsg->lastConfigIndex >= SYNC_INDEX_BEGIN) {
@@ -782,7 +887,7 @@ int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
         // condition 3
         // force close
         snapshotReceiverForceStop(pReceiver);
-        needRsp = false;
+        bool needRsp = false;
 
       } else if (pMsg->seq > SYNC_SNAPSHOT_SEQ_BEGIN && pMsg->seq < SYNC_SNAPSHOT_SEQ_END) {
         // condition 4
@@ -790,7 +895,7 @@ int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
         if (pMsg->seq == pReceiver->ack + 1) {
           snapshotReceiverGotData(pReceiver, pMsg);
         }
-        needRsp = true;
+        bool needRsp = true;
 
       } else {
         // error log
@@ -805,26 +910,6 @@ int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
         return -1;
       }
 
-      // send ack
-      if (needRsp) {
-        // build msg
-        SyncSnapshotRsp *pRspMsg = syncSnapshotRspBuild(pSyncNode->vgId);
-        pRspMsg->srcId = pSyncNode->myRaftId;
-        pRspMsg->destId = pMsg->srcId;
-        pRspMsg->term = pSyncNode->pRaftStore->currentTerm;
-        pRspMsg->lastIndex = pMsg->lastIndex;
-        pRspMsg->lastTerm = pMsg->lastTerm;
-        pRspMsg->ack = pReceiver->ack;  // receiver maybe already closed
-        pRspMsg->code = 0;
-        pRspMsg->privateTerm = pReceiver->privateTerm;  // receiver maybe already closed
-
-        // send msg
-        SRpcMsg rpcMsg;
-        syncSnapshotRsp2RpcMsg(pRspMsg, &rpcMsg);
-        syncNodeSendMsgById(&(pRspMsg->destId), pSyncNode, &rpcMsg);
-        syncSnapshotRspDestroy(pRspMsg);
-      }
-
     } else {
       // error log
       do {
@@ -849,6 +934,52 @@ int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
   return 0;
 }
 
+int32_t syncNodeOnSnapshotReplyPre(SSyncNode *pSyncNode, SyncSnapshotRsp *pMsg) {
+  // get sender
+  SSyncSnapshotSender *pSender = syncNodeGetSnapshotSender(pSyncNode, &(pMsg->srcId));
+  ASSERT(pSender != NULL);
+
+  SSnapshot snapshot;
+  pSyncNode->pFsm->FpGetSnapshotInfo(pSyncNode->pFsm, &snapshot);
+
+  // prepare <begin, end>
+  pSender->snapshotParam.start = pMsg->snapBeginIndex;
+  pSender->snapshotParam.end = snapshot.lastApplyIndex;
+
+  if (pMsg->snapBeginIndex > snapshot.lastApplyIndex) {
+    syncNodeErrorLog(pSyncNode, "snapshot last index too small");
+    return -1;
+  }
+
+  // start reader
+  int32_t code = pSyncNode->pFsm->FpSnapshotStartRead(pSyncNode->pFsm, &(pSender->snapshotParam), &(pSender->pReader));
+  if (code != 0) {
+    syncNodeErrorLog(pSyncNode, "create snapshot reader error");
+    return -1;
+  }
+
+  // build begin msg
+  SyncSnapshotSend *pSendMsg = syncSnapshotSendBuild(0, pSender->pSyncNode->vgId);
+  pSendMsg->srcId = pSender->pSyncNode->myRaftId;
+  pSendMsg->destId = (pSender->pSyncNode->replicasId)[pSender->replicaIndex];
+  pSendMsg->term = pSender->pSyncNode->pRaftStore->currentTerm;
+  pSendMsg->beginIndex = pSender->snapshotParam.start;
+  pSendMsg->lastIndex = pSender->snapshot.lastApplyIndex;
+  pSendMsg->lastTerm = pSender->snapshot.lastApplyTerm;
+  pSendMsg->lastConfigIndex = pSender->snapshot.lastConfigIndex;
+  pSendMsg->lastConfig = pSender->lastConfig;
+  pSendMsg->startTime = pSender->startTime;
+  pSendMsg->seq = SYNC_SNAPSHOT_SEQ_BEGIN;
+
+  // send msg
+  SRpcMsg rpcMsg;
+  syncSnapshotSend2RpcMsg(pSendMsg, &rpcMsg);
+  syncNodeSendMsgById(&(pSendMsg->destId), pSender->pSyncNode, &rpcMsg);
+  syncSnapshotSendDestroy(pSendMsg);
+
+  return 0;
+}
+
 // sender on message
 //
 // condition 1 sender receives SYNC_SNAPSHOT_SEQ_END, close sender
@@ -857,8 +988,8 @@ int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SyncSnapshotSend *pMsg) {
 //
 int32_t syncNodeOnSnapshotReply(SSyncNode *pSyncNode, SyncSnapshotRsp *pMsg) {
   // if already drop replica, do not process
-  if (!syncNodeInRaftGroup(pSyncNode, &(pMsg->srcId)) && pSyncNode->state == TAOS_SYNC_STATE_LEADER) {
-    sError("vgId:%d, recv sync-snapshot-rsp, maybe replica already dropped", pSyncNode->vgId);
+  if (!syncNodeInRaftGroup(pSyncNode, &(pMsg->srcId))) {
+    syncLogRecvSyncSnapshotRsp(pSyncNode, pMsg, "maybe replica already dropped");
     return -1;
   }
 
@@ -866,17 +997,26 @@ int32_t syncNodeOnSnapshotReply(SSyncNode *pSyncNode, SyncSnapshotRsp *pMsg) {
   SSyncSnapshotSender *pSender = syncNodeGetSnapshotSender(pSyncNode, &(pMsg->srcId));
   ASSERT(pSender != NULL);
 
+  if (pMsg->startTime != pSender->startTime) {
+    syncLogRecvSyncSnapshotRsp(pSyncNode, pMsg, "sender/receiver start time not match");
+    return -1;
+  }
+
   // state, term, seq/ack
   if (pSyncNode->state == TAOS_SYNC_STATE_LEADER) {
     if (pMsg->term == pSyncNode->pRaftStore->currentTerm) {
-      // condition 1
+      // prepare <begin, end>, send begin msg
+      if (pMsg->ack == SYNC_SNAPSHOT_SEQ_PRE_SNAPSHOT) {
+        syncNodeOnSnapshotReplyPre(pSyncNode, pMsg);
+        return 0;
+      }
+
       // receive ack is finish, close sender
       if (pMsg->ack == SYNC_SNAPSHOT_SEQ_END) {
         snapshotSenderStop(pSender, true);
         return 0;
       }
 
-      // condition 2
       // send next msg
       if (pMsg->ack == pSender->seq) {
         // update sender ack
@@ -922,3 +1062,63 @@ int32_t syncNodeOnSnapshotReply(SSyncNode *pSyncNode, SyncSnapshotRsp *pMsg) {
 
   return 0;
 }
+
+int32_t syncNodeOnPreSnapshot(SSyncNode *ths, SyncPreSnapshot *pMsg) {
+  syncLogRecvSyncPreSnapshot(ths, pMsg, "");
+
+  SyncPreSnapshotReply *pMsgReply = syncPreSnapshotReplyBuild(ths->vgId);
+  pMsgReply->srcId = ths->myRaftId;
+  pMsgReply->destId = pMsg->srcId;
+  pMsgReply->term = ths->pRaftStore->currentTerm;
+
+  SSyncLogStoreData *pData = ths->pLogStore->data;
+  SWal              *pWal = pData->pWal;
+
+  if (syncNodeIsMnode(ths)) {
+    pMsgReply->snapStart = SYNC_INDEX_BEGIN;
+
+  } else {
+    bool    isEmpty = ths->pLogStore->syncLogIsEmpty(ths->pLogStore);
+    int64_t walCommitVer = walGetCommittedVer(pWal);
+
+    if (!isEmpty && ths->commitIndex != walCommitVer) {
+      char logBuf[128];
+      snprintf(logBuf, sizeof(logBuf), "commit not same, wal-commit:%" PRId64 ", commit:%" PRId64 ", ignore",
+               walCommitVer, ths->commitIndex);
+      syncNodeErrorLog(ths, logBuf);
+
+      goto _IGNORE;
+    }
+
+    pMsgReply->snapStart = ths->commitIndex + 1;
+
+    // make local log clean
+    int32_t code = ths->pLogStore->syncLogTruncate(ths->pLogStore, pMsgReply->snapStart);
+    if (code != 0) {
+      syncNodeErrorLog(ths, "truncate wal error");
+      goto _IGNORE;
+    }
+  }
+
+  // can not write behind _RESPONSE
+  SRpcMsg rpcMsg;
+
+_RESPONSE:
+  syncPreSnapshotReply2RpcMsg(pMsgReply, &rpcMsg);
+  syncNodeSendMsgById(&pMsgReply->destId, ths, &rpcMsg);
+
+  syncPreSnapshotReplyDestroy(pMsgReply);
+  return 0;
+
+_IGNORE:
+  syncPreSnapshotReplyDestroy(pMsgReply);
+  return 0;
+}
+
+int32_t syncNodeOnPreSnapshotReply(SSyncNode *ths, SyncPreSnapshotReply *pMsg) {
+  syncLogRecvSyncPreSnapshotReply(ths, pMsg, "");
+
+  // start snapshot
+
+  return 0;
+}
\ No newline at end of file
diff --git a/source/libs/sync/test/CMakeLists.txt b/source/libs/sync/test/CMakeLists.txt
index 26dd32942b7af13fa725a0b449f4b9cd92fa24f1..1b7ec7f0df319b8df2ef974b375cd4d42605118b 100644
--- a/source/libs/sync/test/CMakeLists.txt
+++ b/source/libs/sync/test/CMakeLists.txt
@@ -60,6 +60,8 @@ add_executable(syncRaftCfgIndexTest "")
 add_executable(syncHeartbeatTest "")
 add_executable(syncHeartbeatReplyTest "")
 add_executable(syncLocalCmdTest "")
+add_executable(syncPreSnapshotTest "")
+add_executable(syncPreSnapshotReplyTest "")
 
 
 target_sources(syncTest
@@ -310,6 +312,14 @@ target_sources(syncLocalCmdTest
     PRIVATE
     "syncLocalCmdTest.cpp"
 )
+target_sources(syncPreSnapshotTest
+    PRIVATE
+    "syncPreSnapshotTest.cpp"
+)
+target_sources(syncPreSnapshotReplyTest
+    PRIVATE
+    "syncPreSnapshotReplyTest.cpp"
+)
 
 
 target_include_directories(syncTest
@@ -622,6 +632,16 @@ target_include_directories(syncLocalCmdTest
     "${TD_SOURCE_DIR}/include/libs/sync"
     "${CMAKE_CURRENT_SOURCE_DIR}/../inc"
 )
+target_include_directories(syncPreSnapshotTest
+    PUBLIC
+    "${TD_SOURCE_DIR}/include/libs/sync"
+    "${CMAKE_CURRENT_SOURCE_DIR}/../inc"
+)
+target_include_directories(syncPreSnapshotReplyTest
+    PUBLIC
+    "${TD_SOURCE_DIR}/include/libs/sync"
+    "${CMAKE_CURRENT_SOURCE_DIR}/../inc"
+)
 
 
 target_link_libraries(syncTest
@@ -872,6 +892,14 @@ target_link_libraries(syncLocalCmdTest
     sync
     gtest_main
 )
+target_link_libraries(syncPreSnapshotTest
+    sync
+    gtest_main
+)
+target_link_libraries(syncPreSnapshotReplyTest
+    sync
+    gtest_main
+)
 
 
 enable_testing()
diff --git a/source/libs/sync/test/syncConfigChangeSnapshotTest.cpp b/source/libs/sync/test/syncConfigChangeSnapshotTest.cpp
index 472aa557127afe7e2570f67fda79ade698007835..dcf7249d30abd5c012715ddb7f7f464988108128 100644
--- a/source/libs/sync/test/syncConfigChangeSnapshotTest.cpp
+++ b/source/libs/sync/test/syncConfigChangeSnapshotTest.cpp
@@ -157,6 +157,7 @@ SSyncFSM* createFsm() {
   SSyncFSM* pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(SSyncFSM));
   memset(pFsm, 0, sizeof(*pFsm));
 
+#if 0
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
@@ -171,6 +172,7 @@ SSyncFSM* createFsm() {
   pFsm->FpSnapshotDoWrite = SnapshotDoWrite;
 
   pFsm->FpReConfigCb = ReConfigCb;
+#endif
 
   return pFsm;
 }
diff --git a/source/libs/sync/test/syncConfigChangeTest.cpp b/source/libs/sync/test/syncConfigChangeTest.cpp
index 9c6f966fffc3a84c3000c6c389fa5b91fc1e6ee8..c5548d25d45c2974016ff1622429db8b62f086fe 100644
--- a/source/libs/sync/test/syncConfigChangeTest.cpp
+++ b/source/libs/sync/test/syncConfigChangeTest.cpp
@@ -33,7 +33,7 @@ void init() {
 
 void cleanup() { walCleanUp(); }
 
-void CommitCb(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
+void CommitCb(const struct SSyncFSM* pFsm, const SRpcMsg* pMsg, const SFsmCbMeta cbMeta) {
   SyncIndex beginIndex = SYNC_INDEX_INVALID;
   if (pFsm->FpGetSnapshotInfo != NULL) {
     SSnapshot snapshot;
@@ -52,7 +52,7 @@ void CommitCb(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
   }
 }
 
-void PreCommitCb(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
+void PreCommitCb(const struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
   char logBuf[256] = {0};
   snprintf(logBuf, sizeof(logBuf),
            "==callback== ==PreCommitCb== pFsm:%p, index:%" PRId64 ", isWeak:%d, code:%d, state:%d %s flag:%" PRIu64
@@ -61,7 +61,7 @@ void PreCommitCb(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta)
   syncRpcMsgLog2(logBuf, (SRpcMsg*)pMsg);
 }
 
-void RollBackCb(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
+void RollBackCb(const struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
   char logBuf[256];
   snprintf(logBuf, sizeof(logBuf),
            "==callback== ==RollBackCb== pFsm:%p, index:%" PRId64 ", isWeak:%d, code:%d, state:%d %s flag:%" PRIu64 "\n",
@@ -69,7 +69,7 @@ void RollBackCb(struct SSyncFSM* pFsm, const SRpcMsg* pMsg, SFsmCbMeta cbMeta) {
   syncRpcMsgLog2(logBuf, (SRpcMsg*)pMsg);
 }
 
-int32_t GetSnapshotCb(struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
+int32_t GetSnapshotCb(const struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
   pSnapshot->data = NULL;
   pSnapshot->lastApplyIndex = gSnapshotLastApplyIndex;
   pSnapshot->lastApplyTerm = 100;
@@ -87,6 +87,7 @@ SSyncFSM* createFsm() {
   SSyncFSM* pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(SSyncFSM));
   memset(pFsm, 0, sizeof(*pFsm));
 
+#if 0
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
@@ -95,6 +96,7 @@ SSyncFSM* createFsm() {
   pFsm->FpRestoreFinishCb = RestoreFinishCb;
 
   pFsm->FpReConfigCb = ReConfigCb;
+#endif
 
   return pFsm;
 }
diff --git a/source/libs/sync/test/syncEnvTest.cpp b/source/libs/sync/test/syncEnvTest.cpp
index 404ab32d582c3347720bc6997fa154be82c521c0..a220c2aed4bf0c3cb815f5ee8a646d94f3999d07 100644
--- a/source/libs/sync/test/syncEnvTest.cpp
+++ b/source/libs/sync/test/syncEnvTest.cpp
@@ -26,12 +26,12 @@ int main() {
   assert(ret == 0);
 
   for (int i = 0; i < 5; ++i) {
-    ret = syncEnvStartTimer();
+    //ret = syncEnvStartTimer();
     assert(ret == 0);
 
     taosMsleep(5000);
 
-    ret = syncEnvStopTimer();
+    //ret = syncEnvStopTimer();
     assert(ret == 0);
 
     taosMsleep(5000);
diff --git a/source/libs/sync/test/syncPreSnapshotReplyTest.cpp b/source/libs/sync/test/syncPreSnapshotReplyTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..a30dcc2c545640a7bfe181727465a922107713a5
--- /dev/null
+++ b/source/libs/sync/test/syncPreSnapshotReplyTest.cpp
@@ -0,0 +1,99 @@
+
+#include <gtest/gtest.h>
+#include <stdio.h>
+#include "syncIO.h"
+#include "syncInt.h"
+#include "syncMessage.h"
+#include "syncUtil.h"
+
+void logTest() {
+  sTrace("--- sync log test: trace");
+  sDebug("--- sync log test: debug");
+  sInfo("--- sync log test: info");
+  sWarn("--- sync log test: warn");
+  sError("--- sync log test: error");
+  sFatal("--- sync log test: fatal");
+}
+
+SyncPreSnapshotReply *createMsg() {
+  SyncPreSnapshotReply *pMsg = syncPreSnapshotReplyBuild(789);
+  pMsg->srcId.addr = syncUtilAddr2U64("127.0.0.1", 1234);
+  pMsg->srcId.vgId = 100;
+  pMsg->destId.addr = syncUtilAddr2U64("127.0.0.1", 5678);
+  pMsg->destId.vgId = 100;
+  pMsg->term = 9527;
+  pMsg->snapStart = 12306;
+  return pMsg;
+}
+
+void test1() {
+  SyncPreSnapshotReply *pMsg = createMsg();
+  syncPreSnapshotReplyLog2((char *)"test1:", pMsg);
+  syncPreSnapshotReplyDestroy(pMsg);
+}
+
+void test2() {
+  SyncPreSnapshotReply *pMsg = createMsg();
+  uint32_t       len = pMsg->bytes;
+  char *         serialized = (char *)taosMemoryMalloc(len);
+  syncPreSnapshotReplySerialize(pMsg, serialized, len);
+  SyncPreSnapshotReply *pMsg2 = syncPreSnapshotReplyBuild(789);
+  syncPreSnapshotReplyDeserialize(serialized, len, pMsg2);
+  syncPreSnapshotReplyLog2((char *)"test2: syncPreSnapshotReplySerialize -> syncPreSnapshotReplyDeserialize ", pMsg2);
+
+  taosMemoryFree(serialized);
+  syncPreSnapshotReplyDestroy(pMsg);
+  syncPreSnapshotReplyDestroy(pMsg2);
+}
+
+void test3() {
+  SyncPreSnapshotReply *pMsg = createMsg();
+  uint32_t       len;
+  char *         serialized = syncPreSnapshotReplySerialize2(pMsg, &len);
+  SyncPreSnapshotReply *pMsg2 = syncPreSnapshotReplyDeserialize2(serialized, len);
+  syncPreSnapshotReplyLog2((char *)"test3: syncPreSnapshotReplySerialize2 -> syncPreSnapshotReplyDeserialize2 ", pMsg2);
+
+  taosMemoryFree(serialized);
+  syncPreSnapshotReplyDestroy(pMsg);
+  syncPreSnapshotReplyDestroy(pMsg2);
+}
+
+void test4() {
+  SyncPreSnapshotReply *pMsg = createMsg();
+  SRpcMsg        rpcMsg;
+  syncPreSnapshotReply2RpcMsg(pMsg, &rpcMsg);
+  SyncPreSnapshotReply *pMsg2 = (SyncPreSnapshotReply *)taosMemoryMalloc(rpcMsg.contLen);
+  syncPreSnapshotReplyFromRpcMsg(&rpcMsg, pMsg2);
+  syncPreSnapshotReplyLog2((char *)"test4: syncPreSnapshotReply2RpcMsg -> syncPreSnapshotReplyFromRpcMsg ", pMsg2);
+
+  rpcFreeCont(rpcMsg.pCont);
+  syncPreSnapshotReplyDestroy(pMsg);
+  syncPreSnapshotReplyDestroy(pMsg2);
+}
+
+void test5() {
+  SyncPreSnapshotReply *pMsg = createMsg();
+  SRpcMsg        rpcMsg;
+  syncPreSnapshotReply2RpcMsg(pMsg, &rpcMsg);
+  SyncPreSnapshotReply *pMsg2 = syncPreSnapshotReplyFromRpcMsg2(&rpcMsg);
+  syncPreSnapshotReplyLog2((char *)"test5: syncPreSnapshotReply2RpcMsg -> syncPreSnapshotReplyFromRpcMsg2 ", pMsg2);
+
+  rpcFreeCont(rpcMsg.pCont);
+  syncPreSnapshotReplyDestroy(pMsg);
+  syncPreSnapshotReplyDestroy(pMsg2);
+}
+
+int main() {
+  tsAsyncLog = 0;
+  sDebugFlag = DEBUG_TRACE + DEBUG_SCREEN + DEBUG_FILE;
+  gRaftDetailLog = true;
+  logTest();
+
+  test1();
+  test2();
+  test3();
+  test4();
+  test5();
+
+  return 0;
+}
diff --git a/source/libs/sync/test/syncPreSnapshotTest.cpp b/source/libs/sync/test/syncPreSnapshotTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..03894dfa84f246de85c934556e00370ca2d20549
--- /dev/null
+++ b/source/libs/sync/test/syncPreSnapshotTest.cpp
@@ -0,0 +1,97 @@
+#include <gtest/gtest.h>
+#include <stdio.h>
+#include "syncIO.h"
+#include "syncInt.h"
+#include "syncMessage.h"
+#include "syncUtil.h"
+
+void logTest() {
+  sTrace("--- sync log test: trace");
+  sDebug("--- sync log test: debug");
+  sInfo("--- sync log test: info");
+  sWarn("--- sync log test: warn");
+  sError("--- sync log test: error");
+  sFatal("--- sync log test: fatal");
+}
+
+SyncPreSnapshot *createMsg() {
+  SyncPreSnapshot *pMsg = syncPreSnapshotBuild(789);
+  pMsg->srcId.addr = syncUtilAddr2U64("127.0.0.1", 1234);
+  pMsg->srcId.vgId = 100;
+  pMsg->destId.addr = syncUtilAddr2U64("127.0.0.1", 5678);
+  pMsg->destId.vgId = 100;
+  pMsg->term = 9527;
+  return pMsg;
+}
+
+void test1() {
+  SyncPreSnapshot *pMsg = createMsg();
+  syncPreSnapshotLog2((char *)"test1:", pMsg);
+  syncPreSnapshotDestroy(pMsg);
+}
+
+void test2() {
+  SyncPreSnapshot *pMsg = createMsg();
+  uint32_t       len = pMsg->bytes;
+  char *         serialized = (char *)taosMemoryMalloc(len);
+  syncPreSnapshotSerialize(pMsg, serialized, len);
+  SyncPreSnapshot *pMsg2 = syncPreSnapshotBuild(789);
+  syncPreSnapshotDeserialize(serialized, len, pMsg2);
+  syncPreSnapshotLog2((char *)"test2: syncPreSnapshotSerialize -> syncPreSnapshotDeserialize ", pMsg2);
+
+  taosMemoryFree(serialized);
+  syncPreSnapshotDestroy(pMsg);
+  syncPreSnapshotDestroy(pMsg2);
+}
+
+void test3() {
+  SyncPreSnapshot *pMsg = createMsg();
+  uint32_t       len;
+  char *         serialized = syncPreSnapshotSerialize2(pMsg, &len);
+  SyncPreSnapshot *pMsg2 = syncPreSnapshotDeserialize2(serialized, len);
+  syncPreSnapshotLog2((char *)"test3: syncPreSnapshotSerialize2 -> syncPreSnapshotDeserialize2 ", pMsg2);
+
+  taosMemoryFree(serialized);
+  syncPreSnapshotDestroy(pMsg);
+  syncPreSnapshotDestroy(pMsg2);
+}
+
+void test4() {
+  SyncPreSnapshot *pMsg = createMsg();
+  SRpcMsg        rpcMsg;
+  syncPreSnapshot2RpcMsg(pMsg, &rpcMsg);
+  SyncPreSnapshot *pMsg2 = (SyncPreSnapshot *)taosMemoryMalloc(rpcMsg.contLen);
+  syncPreSnapshotFromRpcMsg(&rpcMsg, pMsg2);
+  syncPreSnapshotLog2((char *)"test4: syncPreSnapshot2RpcMsg -> syncPreSnapshotFromRpcMsg ", pMsg2);
+
+  rpcFreeCont(rpcMsg.pCont);
+  syncPreSnapshotDestroy(pMsg);
+  syncPreSnapshotDestroy(pMsg2);
+}
+
+void test5() {
+  SyncPreSnapshot *pMsg = createMsg();
+  SRpcMsg        rpcMsg;
+  syncPreSnapshot2RpcMsg(pMsg, &rpcMsg);
+  SyncPreSnapshot *pMsg2 = syncPreSnapshotFromRpcMsg2(&rpcMsg);
+  syncPreSnapshotLog2((char *)"test5: syncPreSnapshot2RpcMsg -> syncPreSnapshotFromRpcMsg2 ", pMsg2);
+
+  rpcFreeCont(rpcMsg.pCont);
+  syncPreSnapshotDestroy(pMsg);
+  syncPreSnapshotDestroy(pMsg2);
+}
+
+int main() {
+  tsAsyncLog = 0;
+  sDebugFlag = DEBUG_TRACE + DEBUG_SCREEN + DEBUG_FILE;
+  gRaftDetailLog = true;
+  logTest();
+
+  test1();
+  test2();
+  test3();
+  test4();
+  test5();
+
+  return 0;
+}
diff --git a/source/libs/sync/test/syncRaftLogTest2.cpp b/source/libs/sync/test/syncRaftLogTest2.cpp
index 0cb9b51fba35d0457cc42b9992c472ed64831c36..78c08a6d8d9f0d832773f0f065dfffcbbf281825 100644
--- a/source/libs/sync/test/syncRaftLogTest2.cpp
+++ b/source/libs/sync/test/syncRaftLogTest2.cpp
@@ -25,7 +25,7 @@ const char*    pWalPath = "./syncLogStoreTest_wal";
 SyncIndex gSnapshotLastApplyIndex;
 SyncIndex gSnapshotLastApplyTerm;
 
-int32_t GetSnapshotCb(struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
+int32_t GetSnapshotCb(const struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
   pSnapshot->data = NULL;
   pSnapshot->lastApplyIndex = gSnapshotLastApplyIndex;
   pSnapshot->lastApplyTerm = gSnapshotLastApplyTerm;
diff --git a/source/libs/sync/test/syncRaftLogTest3.cpp b/source/libs/sync/test/syncRaftLogTest3.cpp
index 1171ef8785183af3a2ad0b3fc31e670c87b7eaab..cf862feb2a9011b233eae6dc1bcbd2d7a3af4992 100644
--- a/source/libs/sync/test/syncRaftLogTest3.cpp
+++ b/source/libs/sync/test/syncRaftLogTest3.cpp
@@ -27,7 +27,7 @@ const char*    pWalPath = "./syncLogStoreTest_wal";
 SyncIndex gSnapshotLastApplyIndex;
 SyncIndex gSnapshotLastApplyTerm;
 
-int32_t GetSnapshotCb(struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
+int32_t GetSnapshotCb(const struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
   pSnapshot->data = NULL;
   pSnapshot->lastApplyIndex = gSnapshotLastApplyIndex;
   pSnapshot->lastApplyTerm = gSnapshotLastApplyTerm;
diff --git a/source/libs/sync/test/syncReplicateTest.cpp b/source/libs/sync/test/syncReplicateTest.cpp
index 8c5267b324646c11bcb30edb60ce245ae6fbebcb..7506ae19bdf1a6f43e354a3d7e4eff792d2bb00f 100644
--- a/source/libs/sync/test/syncReplicateTest.cpp
+++ b/source/libs/sync/test/syncReplicateTest.cpp
@@ -74,10 +74,14 @@ int32_t GetSnapshotCb(struct SSyncFSM* pFsm, SSnapshot* pSnapshot) {
 
 SSyncFSM* createFsm() {
   SSyncFSM* pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(SSyncFSM));
+
+#if 0 
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
   pFsm->FpGetSnapshotInfo = GetSnapshotCb;
+#endif
+
   return pFsm;
 }
 
diff --git a/source/libs/sync/test/syncSnapshotReceiverTest.cpp b/source/libs/sync/test/syncSnapshotReceiverTest.cpp
index 0f8e76f12167d71ea6c5919dbff5e567033b580a..6eb854874073c14e04ac86fc9640eba105d6058c 100644
--- a/source/libs/sync/test/syncSnapshotReceiverTest.cpp
+++ b/source/libs/sync/test/syncSnapshotReceiverTest.cpp
@@ -37,9 +37,12 @@ SSyncSnapshotReceiver* createReceiver() {
   SSyncNode* pSyncNode = (SSyncNode*)taosMemoryMalloc(sizeof(*pSyncNode));
   pSyncNode->pRaftStore = (SRaftStore*)taosMemoryMalloc(sizeof(*(pSyncNode->pRaftStore)));
   pSyncNode->pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(*(pSyncNode->pFsm)));
+
+#if 0 
   pSyncNode->pFsm->FpSnapshotStartWrite = SnapshotStartWrite;
   pSyncNode->pFsm->FpSnapshotStopWrite = SnapshotStopWrite;
   pSyncNode->pFsm->FpSnapshotDoWrite = SnapshotDoWrite;
+#endif
 
   SRaftId id;
   id.addr = syncUtilAddr2U64("1.2.3.4", 99);
@@ -50,7 +53,6 @@ SSyncSnapshotReceiver* createReceiver() {
   pReceiver->ack = 20;
   pReceiver->pWriter = (void*)0x11;
   pReceiver->term = 66;
-  pReceiver->privateTerm = 99;
 
   return pReceiver;
 }
diff --git a/source/libs/sync/test/syncSnapshotRspTest.cpp b/source/libs/sync/test/syncSnapshotRspTest.cpp
index 89348da6175403f36d9edf25d70a587e3e3617f7..63905c2182e1fc9b2c66bcfd0a8429d62305d9e0 100644
--- a/source/libs/sync/test/syncSnapshotRspTest.cpp
+++ b/source/libs/sync/test/syncSnapshotRspTest.cpp
@@ -21,7 +21,7 @@ SyncSnapshotRsp *createMsg() {
   pMsg->destId.addr = syncUtilAddr2U64("127.0.0.1", 5678);
   pMsg->destId.vgId = 100;
   pMsg->term = 11;
-  pMsg->privateTerm = 99;
+  pMsg->startTime = 99;
   pMsg->lastIndex = 22;
   pMsg->lastTerm = 33;
   pMsg->ack = 44;
diff --git a/source/libs/sync/test/syncSnapshotSendTest.cpp b/source/libs/sync/test/syncSnapshotSendTest.cpp
index 6fcfa6f6c490134e13a581963b200e0d7c466d42..83f1dfebb3893cc73ea36826c3ee353932042e14 100644
--- a/source/libs/sync/test/syncSnapshotSendTest.cpp
+++ b/source/libs/sync/test/syncSnapshotSendTest.cpp
@@ -21,7 +21,6 @@ SyncSnapshotSend *createMsg() {
   pMsg->destId.addr = syncUtilAddr2U64("127.0.0.1", 5678);
   pMsg->destId.vgId = 100;
   pMsg->term = 11;
-  pMsg->privateTerm = 99;
   pMsg->lastIndex = 22;
   pMsg->lastTerm = 33;
 
diff --git a/source/libs/sync/test/syncSnapshotSenderTest.cpp b/source/libs/sync/test/syncSnapshotSenderTest.cpp
index 8d1f83b3b19cae7527dc83be0cf6d70f9748bae6..7b2c13463cf28321add905f6baa729d21e27f2d3 100644
--- a/source/libs/sync/test/syncSnapshotSenderTest.cpp
+++ b/source/libs/sync/test/syncSnapshotSenderTest.cpp
@@ -37,10 +37,13 @@ SSyncSnapshotSender* createSender() {
   SSyncNode* pSyncNode = (SSyncNode*)taosMemoryMalloc(sizeof(*pSyncNode));
   pSyncNode->pRaftStore = (SRaftStore*)taosMemoryMalloc(sizeof(*(pSyncNode->pRaftStore)));
   pSyncNode->pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(*(pSyncNode->pFsm)));
+
+ #if 0 
   pSyncNode->pFsm->FpSnapshotStartRead = SnapshotStartRead;
   pSyncNode->pFsm->FpSnapshotStopRead = SnapshotStopRead;
   pSyncNode->pFsm->FpSnapshotDoRead = SnapshotDoRead;
   pSyncNode->pFsm->FpGetSnapshotInfo = GetSnapshot;
+#endif
 
   SSyncSnapshotSender* pSender = snapshotSenderCreate(pSyncNode, 2);
   pSender->start = true;
@@ -55,7 +58,8 @@ SSyncSnapshotSender* createSender() {
   pSender->snapshot.lastApplyTerm = 88;
   pSender->sendingMS = 77;
   pSender->term = 66;
-  pSender->privateTerm = 99;
+  
+  //pSender->privateTerm = 99;
 
   return pSender;
 }
diff --git a/source/libs/sync/test/syncSnapshotTest.cpp b/source/libs/sync/test/syncSnapshotTest.cpp
index 34039700c3752858f337fb08723b4aa13daf045b..ea90621bacb561410cd426eb4939850927ffc01e 100644
--- a/source/libs/sync/test/syncSnapshotTest.cpp
+++ b/source/libs/sync/test/syncSnapshotTest.cpp
@@ -33,7 +33,7 @@ SyncIndex  snapshotLastApplyIndex = SYNC_INDEX_INVALID;
 const char *pDir = "./syncSnapshotTest";
 const char *pWalDir = "./syncSnapshotTest_wal";
 
-void CommitCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
+void CommitCb(const struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
   SyncIndex beginIndex = SYNC_INDEX_INVALID;
   if (pFsm->FpGetSnapshotInfo != NULL) {
     SSnapshot snapshot;
@@ -52,7 +52,7 @@ void CommitCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
   }
 }
 
-void PreCommitCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
+void PreCommitCb(const struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
   char logBuf[256];
   snprintf(logBuf, sizeof(logBuf),
            "==callback== ==PreCommitCb== pFsm:%p, index:%" PRId64 ", isWeak:%d, code:%d, state:%d %s \n", pFsm,
@@ -60,7 +60,7 @@ void PreCommitCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta)
   syncRpcMsgLog2(logBuf, (SRpcMsg *)pMsg);
 }
 
-void RollBackCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
+void RollBackCb(const struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
   char logBuf[256];
   snprintf(logBuf, sizeof(logBuf),
            "==callback== ==RollBackCb== pFsm:%p, index:%" PRId64 ", isWeak:%d, code:%d, state:%d %s \n", pFsm,
@@ -68,7 +68,7 @@ void RollBackCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
   syncRpcMsgLog2(logBuf, (SRpcMsg *)pMsg);
 }
 
-int32_t GetSnapshotCb(struct SSyncFSM *pFsm, SSnapshot *pSnapshot) {
+int32_t GetSnapshotCb(const struct SSyncFSM *pFsm, SSnapshot *pSnapshot) {
   pSnapshot->data = NULL;
   pSnapshot->lastApplyIndex = snapshotLastApplyIndex;
   pSnapshot->lastApplyTerm = 100;
@@ -78,10 +78,14 @@ int32_t GetSnapshotCb(struct SSyncFSM *pFsm, SSnapshot *pSnapshot) {
 void initFsm() {
   pFsm = (SSyncFSM *)taosMemoryMalloc(sizeof(SSyncFSM));
   memset(pFsm, 0, sizeof(*pFsm));
+
+#if 0 
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
   pFsm->FpGetSnapshotInfo = GetSnapshotCb;
+#endif
+
 }
 
 SSyncNode *syncNodeInit() {
diff --git a/source/libs/sync/test/syncTestTool.cpp b/source/libs/sync/test/syncTestTool.cpp
index 3a9ca7ad4d50d2562838d5c1be7b584089f8434e..e6f6006410307ffd8f524e0919b7a2b6dac150cc 100644
--- a/source/libs/sync/test/syncTestTool.cpp
+++ b/source/libs/sync/test/syncTestTool.cpp
@@ -177,6 +177,7 @@ SSyncFSM* createFsm() {
   SSyncFSM* pFsm = (SSyncFSM*)taosMemoryMalloc(sizeof(SSyncFSM));
   memset(pFsm, 0, sizeof(*pFsm));
 
+#if 0
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
@@ -193,6 +194,7 @@ SSyncFSM* createFsm() {
   pFsm->FpSnapshotDoWrite = SnapshotDoWrite;
 
   pFsm->FpLeaderTransferCb = LeaderTransferCb;
+#endif
 
   return pFsm;
 }
diff --git a/source/libs/sync/test/syncWriteTest.cpp b/source/libs/sync/test/syncWriteTest.cpp
index 829087113106da543707f57fcb4aaadf700628a1..cafecabc4d0baba1133918dcbbf77311fda29316 100644
--- a/source/libs/sync/test/syncWriteTest.cpp
+++ b/source/libs/sync/test/syncWriteTest.cpp
@@ -57,9 +57,13 @@ void RollBackCb(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbMeta) {
 
 void initFsm() {
   pFsm = (SSyncFSM *)taosMemoryMalloc(sizeof(SSyncFSM));
+
+#if 0
   pFsm->FpCommitCb = CommitCb;
   pFsm->FpPreCommitCb = PreCommitCb;
   pFsm->FpRollBackCb = RollBackCb;
+#endif
+
 }
 
 SSyncNode *syncNodeInit() {