diff --git a/src/client/src/tscAsync.c b/src/client/src/tscAsync.c
index e380206696..6ab4eeaa8a 100644
--- a/src/client/src/tscAsync.c
+++ b/src/client/src/tscAsync.c
@@ -54,7 +54,7 @@ void doAsyncQuery(STscObj* pObj, SSqlObj* pSql, void (*fp)(), void* param, const
     return;
   }
 
-  strtolower(pSql->sqlstr, sqlstr);
+  strntolower(pSql->sqlstr, sqlstr, sqlLen);
 
   tscDebugL("%p SQL: %s", pSql, pSql->sqlstr);
   pSql->cmd.curSql = pSql->sqlstr;
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 5d5e546943..0677463d8d 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -263,12 +263,29 @@ TAOS_RES* taos_query(TAOS *taos, const char *sqlstr) {
   return pSql;
 }
 TAOS_RES* taos_query_c(TAOS *taos, const char *sqlstr, uint32_t sqlLen) {
-  char* buf = malloc(sqlLen + 1);
-  buf[sqlLen] = 0;
-  strncpy(buf, sqlstr, sqlLen);
-  TAOS_RES *res = taos_query(taos, buf);
-  free(buf);
-  return res; 
+  STscObj *pObj = (STscObj *)taos;
+  if (pObj == NULL || pObj->signature != pObj) {
+    terrno = TSDB_CODE_TSC_DISCONNECTED;
+    return NULL;
+  }
+  
+  if (sqlLen > tsMaxSQLStringLen) {
+    tscError("sql string exceeds max length:%d", tsMaxSQLStringLen);
+    terrno = TSDB_CODE_TSC_INVALID_SQL;
+    return NULL;
+  }
+  
+  SSqlObj* pSql = calloc(1, sizeof(SSqlObj));
+  if (pSql == NULL) {
+    tscError("failed to malloc sqlObj");
+    terrno = TSDB_CODE_TSC_OUT_OF_MEMORY;
+    return NULL;
+  }
+  
+  doAsyncQuery(pObj, pSql, waitForQueryRsp, taos, sqlstr, sqlLen);
+
+  tsem_wait(&pSql->rspSem);
+  return pSql; 
 }
 int taos_result_precision(TAOS_RES *res) {
   SSqlObj *pSql = (SSqlObj *)res;
diff --git a/src/common/src/tdataformat.c b/src/common/src/tdataformat.c
index 12ea4ad78d..719d80aa77 100644
--- a/src/common/src/tdataformat.c
+++ b/src/common/src/tdataformat.c
@@ -318,7 +318,7 @@ SDataCols *tdNewDataCols(int maxRowSize, int maxCols, int maxRows) {
   pCols->maxPoints = maxRows;
   pCols->bufSize = maxRowSize * maxRows;
 
-  pCols->buf = malloc(pCols->bufSize);
+  pCols->buf = calloc(1, pCols->bufSize);
   if (pCols->buf == NULL) {
     free(pCols);
     return NULL;
diff --git a/src/dnode/src/dnodeMgmt.c b/src/dnode/src/dnodeMgmt.c
index 86a222b3e6..8e1696c802 100644
--- a/src/dnode/src/dnodeMgmt.c
+++ b/src/dnode/src/dnodeMgmt.c
@@ -399,7 +399,7 @@ static void* dnodeParseVnodeMsg(SRpcMsg *rpcMsg) {
 static int32_t dnodeProcessCreateVnodeMsg(SRpcMsg *rpcMsg) {
   SMDCreateVnodeMsg *pCreate = dnodeParseVnodeMsg(rpcMsg);
 
-  void *pVnode = vnodeAcquireVnode(pCreate->cfg.vgId);
+  void *pVnode = vnodeAcquire(pCreate->cfg.vgId);
   if (pVnode != NULL) {
     dDebug("vgId:%d, already exist, return success", pCreate->cfg.vgId);
     vnodeRelease(pVnode);
@@ -413,7 +413,7 @@ static int32_t dnodeProcessCreateVnodeMsg(SRpcMsg *rpcMsg) {
 static int32_t dnodeProcessAlterVnodeMsg(SRpcMsg *rpcMsg) {
   SMDAlterVnodeMsg *pAlter = dnodeParseVnodeMsg(rpcMsg);
 
-  void *pVnode = vnodeAcquireVnode(pAlter->cfg.vgId);
+  void *pVnode = vnodeAcquire(pAlter->cfg.vgId);
   if (pVnode != NULL) {
     dDebug("vgId:%d, alter vnode msg is received", pAlter->cfg.vgId);
     int32_t code = vnodeAlter(pVnode, pAlter);
diff --git a/src/dnode/src/dnodeVRead.c b/src/dnode/src/dnodeVRead.c
index 66135a93e9..bbea1a5e0b 100644
--- a/src/dnode/src/dnodeVRead.c
+++ b/src/dnode/src/dnodeVRead.c
@@ -91,23 +91,21 @@ void dnodeDispatchToVnodeReadQueue(SRpcMsg *pMsg) {
   int32_t     queuedMsgNum = 0;
   int32_t     leftLen      = pMsg->contLen;
   char        *pCont       = (char *) pMsg->pCont;
-  void        *pVnode;
 
   while (leftLen > 0) {
     SMsgHead *pHead = (SMsgHead *) pCont;
     pHead->vgId    = htonl(pHead->vgId);
     pHead->contLen = htonl(pHead->contLen);
 
-    pVnode = vnodeAcquireVnode(pHead->vgId);
+    taos_queue queue = vnodeAcquireRqueue(pHead->vgId);
 
-    if (pVnode == NULL) {
+    if (queue == NULL) {
       leftLen -= pHead->contLen;
       pCont -= pHead->contLen;
       continue;
     }
 
     // put message into queue
-    taos_queue queue = vnodeGetRqueue(pVnode);
     SReadMsg *pRead = (SReadMsg *)taosAllocateQitem(sizeof(SReadMsg));
     pRead->rpcMsg      = *pMsg;
     pRead->pCont       = pCont;
@@ -175,18 +173,6 @@ void dnodeFreeVnodeRqueue(void *rqueue) {
   // dynamically adjust the number of threads
 }
 
-void dnodePutItemIntoReadQueue(void *pVnode, void *qhandle) {
-  SReadMsg *pRead = (SReadMsg *)taosAllocateQitem(sizeof(SReadMsg));
-  pRead->rpcMsg.msgType = TSDB_MSG_TYPE_QUERY;
-  pRead->pCont = qhandle;
-  pRead->contLen = 0;
-
-  assert(pVnode != NULL);
-  taos_queue queue = vnodeAcquireRqueue(pVnode);
-
-  taosWriteQitem(queue, TAOS_QTYPE_QUERY, pRead);
-}
-
 void dnodeSendRpcReadRsp(void *pVnode, SReadMsg *pRead, int32_t code) {
   SRpcMsg rpcRsp = {
     .handle  = pRead->rpcMsg.handle,
diff --git a/src/dnode/src/dnodeVWrite.c b/src/dnode/src/dnodeVWrite.c
index ba36e537a6..dc09a03e14 100644
--- a/src/dnode/src/dnodeVWrite.c
+++ b/src/dnode/src/dnodeVWrite.c
@@ -104,7 +104,7 @@ void dnodeDispatchToVnodeWriteQueue(SRpcMsg *pMsg) {
   pHead->vgId     = htonl(pHead->vgId);
   pHead->contLen  = htonl(pHead->contLen);
 
-  taos_queue queue = vnodeGetWqueue(pHead->vgId);
+  taos_queue queue = vnodeAcquireWqueue(pHead->vgId);
   if (queue) {
     // put message into queue
     SWriteMsg *pWrite = (SWriteMsg *)taosAllocateQitem(sizeof(SWriteMsg));
diff --git a/src/inc/dnode.h b/src/inc/dnode.h
index 096aae58f2..b561c407a3 100644
--- a/src/inc/dnode.h
+++ b/src/inc/dnode.h
@@ -53,7 +53,6 @@ void *dnodeAllocateVnodeWqueue(void *pVnode);
 void  dnodeFreeVnodeWqueue(void *queue);
 void *dnodeAllocateVnodeRqueue(void *pVnode);
 void  dnodeFreeVnodeRqueue(void *rqueue);
-void  dnodePutItemIntoReadQueue(void *pVnode, void *qhandle);
 void  dnodeSendRpcVnodeWriteRsp(void *pVnode, void *param, int32_t code);
 
 int32_t dnodeAllocateMnodePqueue();
diff --git a/src/inc/tsync.h b/src/inc/tsync.h
index 972db294f6..65b91d87e4 100644
--- a/src/inc/tsync.h
+++ b/src/inc/tsync.h
@@ -79,7 +79,7 @@ typedef void     (*FConfirmForward)(void *ahandle, void *mhandle, int32_t code);
 typedef void     (*FNotifyRole)(void *ahandle, int8_t role);
 
 // when data file is synced successfully, notity app
-typedef void     (*FNotifyFileSynced)(void *ahandle, uint64_t fversion);
+typedef int      (*FNotifyFileSynced)(void *ahandle, uint64_t fversion);
 
 typedef struct {
   int32_t    vgId;      // vgroup ID
diff --git a/src/inc/vnode.h b/src/inc/vnode.h
index 77c72c2451..15ddb6afee 100644
--- a/src/inc/vnode.h
+++ b/src/inc/vnode.h
@@ -22,10 +22,10 @@ extern "C" {
 
 typedef enum _VN_STATUS {
   TAOS_VN_STATUS_INIT,
-  TAOS_VN_STATUS_UPDATING,
   TAOS_VN_STATUS_READY,
   TAOS_VN_STATUS_CLOSING,
-  TAOS_VN_STATUS_DELETING,
+  TAOS_VN_STATUS_UPDATING,
+  TAOS_VN_STATUS_RESET,
 } EVnStatus;
 
 typedef struct {
@@ -47,13 +47,10 @@ int32_t vnodeOpen(int32_t vgId, char *rootDir);
 int32_t vnodeAlter(void *pVnode, SMDCreateVnodeMsg *pVnodeCfg);
 int32_t vnodeClose(int32_t vgId);
 
-void    vnodeRelease(void *pVnode);
-void*   vnodeAcquireVnode(int32_t vgId); // add refcount
-void*   vnodeGetVnode(int32_t vgId);      // keep refcount unchanged
-
-void*   vnodeAcquireRqueue(void *);
-void*   vnodeGetRqueue(void *);
-void*   vnodeGetWqueue(int32_t vgId);
+void*   vnodeAcquire(int32_t vgId);        // add refcount
+void*   vnodeAcquireRqueue(int32_t vgId);  // add refCount, get read queue 
+void*   vnodeAcquireWqueue(int32_t vgId);  // add recCount, get write queue
+void    vnodeRelease(void *pVnode);        // dec refCount
 void*   vnodeGetWal(void *pVnode);
 
 int32_t vnodeProcessWrite(void *pVnode, int qtype, void *pHead, void *item);
diff --git a/src/util/inc/tutil.h b/src/util/inc/tutil.h
index 1ba57bbaaa..f7c69e3973 100644
--- a/src/util/inc/tutil.h
+++ b/src/util/inc/tutil.h
@@ -133,6 +133,8 @@ char **strsplit(char *src, const char *delim, int32_t *num);
 
 char* strtolower(char *dst, const char *src);
 
+char* strntolower(char *dst, const char *src, int32_t n);
+
 int64_t strnatoi(char *num, int32_t len);
 
 //char* strreplace(const char* str, const char* pattern, const char* rep);
diff --git a/src/util/src/tsocket.c b/src/util/src/tsocket.c
index b225dfa36a..5de61a3d57 100644
--- a/src/util/src/tsocket.c
+++ b/src/util/src/tsocket.c
@@ -270,6 +270,14 @@ int taosOpenTcpClientSocket(uint32_t destIp, uint16_t destPort, uint32_t clientI
     return -1;
   }
 
+  /* set REUSEADDR option, so the portnumber can be re-used */
+  int reuse = 1;
+  if (taosSetSockOpt(sockFd, SOL_SOCKET, SO_REUSEADDR, (void *)&reuse, sizeof(reuse)) < 0) {
+    uError("setsockopt SO_REUSEADDR failed: %d (%s)", errno, strerror(errno));
+    close(sockFd);
+    return -1;
+  };
+
   if ( clientIp != 0) {
     memset((char *)&clientAddr, 0, sizeof(clientAddr));
     clientAddr.sin_family = AF_INET;
diff --git a/src/util/src/tutil.c b/src/util/src/tutil.c
index 1a74359f47..c8df34e1cd 100644
--- a/src/util/src/tutil.c
+++ b/src/util/src/tutil.c
@@ -234,6 +234,32 @@ char* strtolower(char *dst, const char *src) {
   *p = 0;
   return dst;
 }
+char* strntolower(char *dst, const char *src, int32_t n) {
+  int esc = 0;
+  char quote = 0, *p = dst, c;
+
+  assert(dst != NULL);
+
+  for (c = *src++; n-- > 0; c = *src++) {
+    if (esc) {
+      esc = 0;
+    } else if (quote) {
+      if (c == '\\') {
+        esc = 1;
+      } else if (c == quote) {
+        quote = 0;
+      }
+    } else if (c >= 'A' && c <= 'Z') {
+      c -= 'A' - 'a';
+    } else if (c == '\'' || c == '"') {
+      quote = c;
+    }
+    *p++ = c;
+  }
+
+  *p = 0;
+  return dst;
+}
 
 char *paGetToken(char *string, char **token, int32_t *tokenLen) {
   char quote = 0;
diff --git a/src/vnode/inc/vnodeInt.h b/src/vnode/inc/vnodeInt.h
index 77db4fd04c..74cfbf1e73 100644
--- a/src/vnode/inc/vnodeInt.h
+++ b/src/vnode/inc/vnodeInt.h
@@ -37,7 +37,7 @@ extern int32_t vDebugFlag;
 typedef struct {
   int32_t      vgId;      // global vnode group ID
   int32_t      refCount;  // reference count
-  int          status; 
+  int8_t       status; 
   int8_t       role;   
   int8_t       accessState;
   int64_t      version;   // current version 
@@ -55,6 +55,8 @@ typedef struct {
   SWalCfg      walCfg;
   void        *qMgmt;
   char        *rootDir;
+  tsem_t       sem;
+  int8_t       dropped;
   char         db[TSDB_DB_NAME_LEN];
 } SVnodeObj;
 
diff --git a/src/vnode/src/vnodeMain.c b/src/vnode/src/vnodeMain.c
index 539f9c6851..bf98824570 100644
--- a/src/vnode/src/vnodeMain.c
+++ b/src/vnode/src/vnodeMain.c
@@ -44,7 +44,7 @@ static int      vnodeProcessTsdbStatus(void *arg, int status);
 static uint32_t vnodeGetFileInfo(void *ahandle, char *name, uint32_t *index, uint32_t eindex, int32_t *size, uint64_t *fversion);
 static int      vnodeGetWalInfo(void *ahandle, char *name, uint32_t *index);
 static void     vnodeNotifyRole(void *ahandle, int8_t role);
-static void     vnodeNotifyFileSynced(void *ahandle, uint64_t fversion);
+static int      vnodeNotifyFileSynced(void *ahandle, uint64_t fversion);
 
 #ifndef _SYNC
 tsync_h syncStart(const SSyncInfo *info) { return NULL; }
@@ -153,7 +153,7 @@ int32_t vnodeDrop(int32_t vgId) {
 
   SVnodeObj *pVnode = *ppVnode;
   vTrace("vgId:%d, vnode will be dropped, refCount:%d", pVnode->vgId, pVnode->refCount);
-  pVnode->status = TAOS_VN_STATUS_DELETING;
+  pVnode->dropped = 1;
   vnodeCleanUp(pVnode);
 
   return TSDB_CODE_SUCCESS;
@@ -164,18 +164,11 @@ int32_t vnodeAlter(void *param, SMDCreateVnodeMsg *pVnodeCfg) {
 
   // vnode in non-ready state and still needs to return success instead of TSDB_CODE_VND_INVALID_STATUS
   // cfgVersion can be corrected by status msg
-  if (pVnode->status != TAOS_VN_STATUS_READY) {
+  if (atomic_val_compare_exchange_8(&pVnode->status, TAOS_VN_STATUS_READY, TAOS_VN_STATUS_UPDATING) != TAOS_VN_STATUS_READY) {
     vDebug("vgId:%d, vnode is not ready, do alter operation later", pVnode->vgId);
     return TSDB_CODE_SUCCESS;
   }
 
-  // the vnode may always fail to synchronize because of it in low cfgVersion
-  // so cannot use the following codes
-  // if (pVnode->syncCfg.replica > 1 && pVnode->role == TAOS_SYNC_ROLE_UNSYNCED) 
-  //   return TSDB_CODE_VND_NOT_SYNCED;
-
-  pVnode->status = TAOS_VN_STATUS_UPDATING;
-
   int32_t code = vnodeSaveCfg(pVnodeCfg);
   if (code != TSDB_CODE_SUCCESS) {
     pVnode->status = TAOS_VN_STATUS_READY;
@@ -194,10 +187,12 @@ int32_t vnodeAlter(void *param, SMDCreateVnodeMsg *pVnodeCfg) {
     return code; 
   } 
 
-  code = tsdbConfigRepo(pVnode->tsdb, &pVnode->tsdbCfg);
-  if (code != TSDB_CODE_SUCCESS) {
-    pVnode->status = TAOS_VN_STATUS_READY;
-    return code; 
+  if (pVnode->tsdb) {
+    code = tsdbConfigRepo(pVnode->tsdb, &pVnode->tsdbCfg);
+    if (code != TSDB_CODE_SUCCESS) {
+      pVnode->status = TAOS_VN_STATUS_READY;
+      return code; 
+    }
   }
 
   pVnode->status = TAOS_VN_STATUS_READY;
@@ -223,6 +218,7 @@ int32_t vnodeOpen(int32_t vnode, char *rootDir) {
   pVnode->tsdbCfg.tsdbId = pVnode->vgId;
   pVnode->rootDir = strdup(rootDir);
   pVnode->accessState = TSDB_VN_ALL_ACCCESS;
+  tsem_init(&pVnode->sem, 0, 0);
 
   int32_t code = vnodeReadCfg(pVnode);
   if (code != TSDB_CODE_SUCCESS) {
@@ -319,7 +315,6 @@ int32_t vnodeClose(int32_t vgId) {
 
   SVnodeObj *pVnode = *ppVnode;
   vDebug("vgId:%d, vnode will be closed", pVnode->vgId);
-  pVnode->status = TAOS_VN_STATUS_CLOSING;
   vnodeCleanUp(pVnode);
 
   return 0;
@@ -334,6 +329,8 @@ void vnodeRelease(void *pVnodeRaw) {
 
   if (refCount > 0) {
     vDebug("vgId:%d, release vnode, refCount:%d", vgId, refCount);
+    if (pVnode->status == TAOS_VN_STATUS_RESET && refCount == 2) 
+      tsem_post(&pVnode->sem);
     return;
   }
 
@@ -344,11 +341,6 @@ void vnodeRelease(void *pVnodeRaw) {
     tsdbCloseRepo(pVnode->tsdb, 1);
   pVnode->tsdb = NULL;
 
-  // stop continuous query
-  if (pVnode->cq) 
-    cqClose(pVnode->cq);
-  pVnode->cq = NULL;
-
   if (pVnode->wal) 
     walClose(pVnode->wal);
   pVnode->wal = NULL;
@@ -363,20 +355,21 @@ void vnodeRelease(void *pVnodeRaw) {
  
   tfree(pVnode->rootDir);
 
-  if (pVnode->status == TAOS_VN_STATUS_DELETING) {
+  if (pVnode->dropped) {
     char rootDir[TSDB_FILENAME_LEN] = {0};
     sprintf(rootDir, "%s/vnode%d", tsVnodeDir, vgId);
     taosMvDir(tsVnodeBakDir, rootDir);
     taosRemoveDir(rootDir);
   }
 
+  tsem_destroy(&pVnode->sem);
   free(pVnode);
 
   int32_t count = taosHashGetSize(tsDnodeVnodesHash);
   vDebug("vgId:%d, vnode is released, vnodes:%d", vgId, count);
 }
 
-void *vnodeGetVnode(int32_t vgId) {
+void *vnodeAcquire(int32_t vgId) {
   SVnodeObj **ppVnode = (SVnodeObj **)taosHashGet(tsDnodeVnodesHash, (const char *)&vgId, sizeof(int32_t));
   if (ppVnode == NULL || *ppVnode == NULL) {
     terrno = TSDB_CODE_VND_INVALID_VGROUP_ID;
@@ -384,35 +377,38 @@ void *vnodeGetVnode(int32_t vgId) {
     return NULL;
   }
 
-  return *ppVnode;
-}
-
-void *vnodeAcquireVnode(int32_t vgId) {
-  SVnodeObj *pVnode = vnodeGetVnode(vgId);
-  if (pVnode == NULL) return pVnode;
-
+  SVnodeObj *pVnode = *ppVnode;
   atomic_add_fetch_32(&pVnode->refCount, 1);
   vDebug("vgId:%d, get vnode, refCount:%d", pVnode->vgId, pVnode->refCount);
 
   return pVnode;
 }
 
-void *vnodeAcquireRqueue(void *param) {
-  SVnodeObj *pVnode = param;
+void *vnodeAcquireRqueue(int32_t vgId) {
+  SVnodeObj *pVnode = vnodeAcquire(vgId);
   if (pVnode == NULL) return NULL;
 
-  atomic_add_fetch_32(&pVnode->refCount, 1);
-  vDebug("vgId:%d, get vnode rqueue, refCount:%d", pVnode->vgId, pVnode->refCount);
-  return ((SVnodeObj *)pVnode)->rqueue;
+  if (pVnode->status == TAOS_VN_STATUS_RESET) {           
+    terrno = TSDB_CODE_VND_INVALID_STATUS;
+    vInfo("vgId:%d, status is in reset", vgId);
+    vnodeRelease(pVnode);
+    return NULL;
+  }
+
+  return pVnode->rqueue;
 }
 
-void *vnodeGetRqueue(void *pVnode) {
-  return ((SVnodeObj *)pVnode)->rqueue;
-}
-
-void *vnodeGetWqueue(int32_t vgId) {
-  SVnodeObj *pVnode = vnodeAcquireVnode(vgId);
+void *vnodeAcquireWqueue(int32_t vgId) {
+  SVnodeObj *pVnode = vnodeAcquire(vgId);
   if (pVnode == NULL) return NULL;
+
+  if (pVnode->status == TAOS_VN_STATUS_RESET) {           
+    terrno = TSDB_CODE_VND_INVALID_STATUS;
+    vInfo("vgId:%d, status is in reset", vgId);
+    vnodeRelease(pVnode);
+    return NULL;
+  }
+  
   return pVnode->wqueue;
 }
 
@@ -484,7 +480,7 @@ void vnodeBuildStatusMsg(void *param) {
 void vnodeSetAccess(SDMVgroupAccess *pAccess, int32_t numOfVnodes) {
   for (int32_t i = 0; i < numOfVnodes; ++i) {
     pAccess[i].vgId = htonl(pAccess[i].vgId);
-    SVnodeObj *pVnode = vnodeAcquireVnode(pAccess[i].vgId);
+    SVnodeObj *pVnode = vnodeAcquire(pAccess[i].vgId);
     if (pVnode != NULL) {
       pVnode->accessState = pAccess[i].accessState;
       if (pVnode->accessState != TSDB_VN_ALL_ACCCESS) {
@@ -498,11 +494,29 @@ void vnodeSetAccess(SDMVgroupAccess *pAccess, int32_t numOfVnodes) {
 static void vnodeCleanUp(SVnodeObj *pVnode) {
   // remove from hash, so new messages wont be consumed
   taosHashRemove(tsDnodeVnodesHash, (const char *)&pVnode->vgId, sizeof(int32_t));
+  int i = 0;
+
+  if (pVnode->status != TAOS_VN_STATUS_INIT) {
+    // it may be in updateing or reset state, then it shall wait
+    while (atomic_val_compare_exchange_8(&pVnode->status, TAOS_VN_STATUS_READY, TAOS_VN_STATUS_CLOSING) != TAOS_VN_STATUS_READY) {
+      if (++i % 1000 == 0) {
+        sched_yield();
+      }
+    }
+  }
 
   // stop replication module
   if (pVnode->sync) {
-    syncStop(pVnode->sync);
+    void *sync = pVnode->sync;
     pVnode->sync = NULL;
+    syncStop(sync);
+  }
+
+  // stop continuous query
+  if (pVnode->cq) {
+    void *cq = pVnode->cq;
+    pVnode->cq = NULL;
+    cqClose(cq);
   }
 
   vTrace("vgId:%d, vnode will cleanup, refCount:%d", pVnode->vgId, pVnode->refCount);
@@ -549,18 +563,25 @@ static void vnodeNotifyRole(void *ahandle, int8_t role) {
     cqStop(pVnode->cq);
 }
 
-static void vnodeNotifyFileSynced(void *ahandle, uint64_t fversion) {
-  SVnodeObj *pVnode = ahandle;
-  vDebug("vgId:%d, data file is synced, fversion:%" PRId64, pVnode->vgId, fversion);
-
-  pVnode->fversion = fversion;
-  pVnode->version = fversion;
-  vnodeSaveVersion(pVnode);
-
+static int vnodeResetTsdb(SVnodeObj *pVnode)
+{
   char rootDir[128] = "\0";
   sprintf(rootDir, "%s/tsdb", pVnode->rootDir);
-  // clsoe tsdb, then open tsdb
-  tsdbCloseRepo(pVnode->tsdb, 0);
+
+  if (atomic_val_compare_exchange_8(&pVnode->status, TAOS_VN_STATUS_READY, TAOS_VN_STATUS_RESET) != TAOS_VN_STATUS_READY)
+    return -1;
+
+  void *tsdb = pVnode->tsdb;
+  pVnode->tsdb = NULL;
+
+  // acquire vnode
+  int32_t refCount = atomic_add_fetch_32(&pVnode->refCount, 1); 
+
+  if (refCount > 2) 
+    tsem_wait(&pVnode->sem);
+
+  // close tsdb, then open tsdb
+  tsdbCloseRepo(tsdb, 0);
   STsdbAppH appH = {0};
   appH.appH = (void *)pVnode;
   appH.notifyStatus = vnodeProcessTsdbStatus;
@@ -569,6 +590,22 @@ static void vnodeNotifyFileSynced(void *ahandle, uint64_t fversion) {
   appH.cqDropFunc = cqDrop;
   appH.configFunc = dnodeSendCfgTableToRecv;
   pVnode->tsdb = tsdbOpenRepo(rootDir, &appH);
+
+  pVnode->status = TAOS_VN_STATUS_READY;
+  vnodeRelease(pVnode);  
+
+  return 0;
+}
+
+static int vnodeNotifyFileSynced(void *ahandle, uint64_t fversion) {
+  SVnodeObj *pVnode = ahandle;
+  vDebug("vgId:%d, data file is synced, fversion:%" PRId64, pVnode->vgId, fversion);
+
+  pVnode->fversion = fversion;
+  pVnode->version = fversion;
+  vnodeSaveVersion(pVnode);
+
+  return vnodeResetTsdb(pVnode);
 }
 
 static int32_t vnodeSaveCfg(SMDCreateVnodeMsg *pVnodeCfg) {
diff --git a/src/vnode/src/vnodeRead.c b/src/vnode/src/vnodeRead.c
index f529b713cf..973df7c5a1 100644
--- a/src/vnode/src/vnodeRead.c
+++ b/src/vnode/src/vnodeRead.c
@@ -26,6 +26,7 @@
 #include "tsdb.h"
 #include "vnode.h"
 #include "vnodeInt.h"
+#include "tqueue.h"
 
 static int32_t (*vnodeProcessReadMsgFp[TSDB_MSG_TYPE_MAX])(SVnodeObj *pVnode, SReadMsg *pReadMsg);
 static int32_t  vnodeProcessQueryMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg);
@@ -51,6 +52,11 @@ int32_t vnodeProcessRead(void *param, SReadMsg *pReadMsg) {
     return TSDB_CODE_VND_INVALID_STATUS; 
   }
 
+  // tsdb may be in reset state  
+  if (pVnode->tsdb == NULL) return TSDB_CODE_RPC_NOT_READY;
+  if (pVnode->status == TAOS_VN_STATUS_CLOSING)
+    return TSDB_CODE_RPC_NOT_READY;
+
   // TODO: Later, let slave to support query
   if (pVnode->syncCfg.replica > 1 && pVnode->role != TAOS_SYNC_ROLE_MASTER) {
     vDebug("vgId:%d, msgType:%s not processed, replica:%d role:%d", pVnode->vgId, taosMsg[msgType], pVnode->syncCfg.replica, pVnode->role);
@@ -60,6 +66,16 @@ int32_t vnodeProcessRead(void *param, SReadMsg *pReadMsg) {
   return (*vnodeProcessReadMsgFp[msgType])(pVnode, pReadMsg);
 }
 
+static void vnodePutItemIntoReadQueue(SVnodeObj *pVnode, void *qhandle) {
+  SReadMsg *pRead = (SReadMsg *)taosAllocateQitem(sizeof(SReadMsg));
+  pRead->rpcMsg.msgType = TSDB_MSG_TYPE_QUERY;
+  pRead->pCont = qhandle;
+  pRead->contLen = 0;
+
+  atomic_add_fetch_32(&pVnode->refCount, 1);
+  taosWriteQitem(pVnode->rqueue, TAOS_QTYPE_QUERY, pRead);
+}
+
 static int32_t vnodeProcessQueryMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg) {
   void    *pCont = pReadMsg->pCont;
   int32_t  contLen = pReadMsg->contLen;
@@ -131,7 +147,7 @@ static int32_t vnodeProcessQueryMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg) {
     if (handle != NULL) {
       vDebug("vgId:%d, QInfo:%p, dnode query msg disposed, register qhandle and return to app", vgId, *handle);
 
-      dnodePutItemIntoReadQueue(pVnode, *handle);
+      vnodePutItemIntoReadQueue(pVnode, *handle);
       qReleaseQInfo(pVnode->qMgmt, (void**) &handle, false);
     }
 
@@ -208,7 +224,7 @@ static int32_t vnodeProcessFetchMsg(SVnodeObj *pVnode, SReadMsg *pReadMsg) {
   } else { // if failed to dump result, free qhandle immediately
     if ((code = qDumpRetrieveResult(*handle, (SRetrieveTableRsp **)&pRet->rsp, &pRet->len)) == TSDB_CODE_SUCCESS) {
       if (qHasMoreResultsToRetrieve(*handle)) {
-        dnodePutItemIntoReadQueue(pVnode, *handle);
+        vnodePutItemIntoReadQueue(pVnode, *handle);
         pRet->qhandle = *handle;
         freeHandle = false;
       } else {
diff --git a/src/vnode/src/vnodeWrite.c b/src/vnode/src/vnodeWrite.c
index 09e4b43ed3..6b9b8ca4fd 100644
--- a/src/vnode/src/vnodeWrite.c
+++ b/src/vnode/src/vnodeWrite.c
@@ -59,13 +59,18 @@ int32_t vnodeProcessWrite(void *param1, int qtype, void *param2, void *item) {
     return TSDB_CODE_VND_NO_WRITE_AUTH;
   }
 
+  // tsdb may be in reset state 
+  if (pVnode->tsdb == NULL) return TSDB_CODE_RPC_NOT_READY;
+  if (pVnode->status == TAOS_VN_STATUS_CLOSING) 
+    return TSDB_CODE_RPC_NOT_READY;
+  
   if (pHead->version == 0) { // from client or CQ 
     if (pVnode->status != TAOS_VN_STATUS_READY) {
       vDebug("vgId:%d, msgType:%s not processed, vnode status is %d", pVnode->vgId, taosMsg[pHead->msgType], pVnode->status);
       return TSDB_CODE_VND_INVALID_STATUS;  // it may be in deleting or closing state
     }
 
-    if (pVnode->syncCfg.replica > 1 && pVnode->role != TAOS_SYNC_ROLE_MASTER) {
+    if (pVnode->role != TAOS_SYNC_ROLE_MASTER) {
       vDebug("vgId:%d, msgType:%s not processed, replica:%d role:%d", pVnode->vgId, taosMsg[pHead->msgType], pVnode->syncCfg.replica, pVnode->role);
       return TSDB_CODE_RPC_NOT_READY;
     }
diff --git a/tests/script/sh/deploy.sh b/tests/script/sh/deploy.sh
index 445baa9e45..b9a9e4f024 100755
--- a/tests/script/sh/deploy.sh
+++ b/tests/script/sh/deploy.sh
@@ -136,6 +136,8 @@ echo "defaultPass         taosdata"       >> $TAOS_CFG
 echo "numOfLogLines       20000000"       >> $TAOS_CFG
 echo "mnodeEqualVnodeNum  0"              >> $TAOS_CFG
 echo "clog                2"              >> $TAOS_CFG
+#echo "cache              1"              >> $TAOS_CFG
+#echo "block              2"              >> $TAOS_CFG
 echo "statusInterval      1"              >> $TAOS_CFG
 echo "numOfTotalVnodes    4"              >> $TAOS_CFG
 echo "maxVgroupsPerDb     4"              >> $TAOS_CFG
diff --git a/tests/script/sh/exec.sh b/tests/script/sh/exec.sh
index 6928039be1..2f294075a1 100755
--- a/tests/script/sh/exec.sh
+++ b/tests/script/sh/exec.sh
@@ -88,7 +88,9 @@ if [ "$EXEC_OPTON" = "start" ]; then
   echo "ExcuteCmd:" $EXE_DIR/taosd -c $CFG_DIR
   
   if [ "$SHELL_OPTION" = "true" ]; then 
-    nohup valgrind --log-file=${LOG_DIR}/valgrind.log --tool=memcheck --leak-check=full --show-reachable=no  --track-origins=yes --show-leak-kinds=all  -v  --workaround-gcc296-bugs=yes   $EXE_DIR/taosd -c $CFG_DIR > /dev/null 2>&1 &   
+    TT=`date +%s`
+    mkdir ${LOG_DIR}/${TT}
+    nohup valgrind --log-file=${LOG_DIR}/${TT}/valgrind.log --tool=memcheck --leak-check=full --show-reachable=no  --track-origins=yes --show-leak-kinds=all  -v  --workaround-gcc296-bugs=yes   $EXE_DIR/taosd -c $CFG_DIR > /dev/null 2>&1 &   
   else
     nohup $EXE_DIR/taosd -c $CFG_DIR > /dev/null 2>&1 & 
   fi
diff --git a/tests/script/unique/vnode/replica2_a_large.sim b/tests/script/unique/vnode/replica2_a_large.sim
new file mode 100644
index 0000000000..801570dd9c
--- /dev/null
+++ b/tests/script/unique/vnode/replica2_a_large.sim
@@ -0,0 +1,103 @@
+system sh/stop_dnodes.sh
+
+system sh/deploy.sh -n dnode1 -i 1
+system sh/deploy.sh -n dnode2 -i 2
+system sh/deploy.sh -n dnode3 -i 3
+system sh/deploy.sh -n dnode4 -i 4
+system sh/cfg.sh -n dnode1 -c wallevel -v 2
+system sh/cfg.sh -n dnode2 -c wallevel -v 2
+system sh/cfg.sh -n dnode3 -c wallevel -v 2
+system sh/cfg.sh -n dnode4 -c wallevel -v 2
+system sh/cfg.sh -n dnode1 -c numOfMnodes -v 1
+system sh/cfg.sh -n dnode2 -c numOfMnodes -v 1
+system sh/cfg.sh -n dnode3 -c numOfMnodes -v 1
+system sh/cfg.sh -n dnode4 -c numOfMnodes -v 1
+system sh/cfg.sh -n dnode1 -c mnodeEqualVnodeNum -v 4
+system sh/cfg.sh -n dnode2 -c mnodeEqualVnodeNum -v 4
+system sh/cfg.sh -n dnode3 -c mnodeEqualVnodeNum -v 4
+system sh/cfg.sh -n dnode4 -c mnodeEqualVnodeNum -v 4
+system sh/cfg.sh -n dnode1 -c debugFlag -v 131
+system sh/cfg.sh -n dnode2 -c debugFlag -v 131
+system sh/cfg.sh -n dnode3 -c debugFlag -v 131
+system sh/cfg.sh -n dnode4 -c debugFlag -v 131
+system sh/cfg.sh -n dnode1 -c arbitrator -v $arbitrator
+system sh/cfg.sh -n dnode2 -c arbitrator -v $arbitrator
+system sh/cfg.sh -n dnode3 -c arbitrator -v $arbitrator
+system sh/cfg.sh -n dnode4 -c arbitrator -v $arbitrator
+
+print ============== step0: start tarbitrator
+system sh/exec_tarbitrator.sh -s start
+
+system sh/exec.sh -n dnode1 -s start
+sleep 3000
+sql connect
+
+sql create dnode $hostname2
+sql create dnode $hostname3
+system sh/exec.sh -n dnode2 -s start -t
+system sh/exec.sh -n dnode3 -s start -t
+sleep 3000
+
+print ========= step1
+sql create database db replica 2 
+#sql create table db.tb1 (ts timestamp, i int)
+#sql create table db.tb2 (ts timestamp, i int)
+#sql create table db.tb3 (ts timestamp, i int)
+#sql create table db.tb4 (ts timestamp, i int)
+#sql insert into db.tb1 values(now, 1)
+#sql select count(*) from db.tb1
+
+sql create database db replica 2 
+sql create table db.tb (ts timestamp, i int)
+sql insert into db.tb values(now, 1)
+sql select count(*) from db.tb
+$lastRows = $rows
+
+print ======== step2
+#run_back unique/vnode/back_insert_many.sim
+run_back unique/vnode/back_insert.sim
+sleep 3000
+
+print ======== step3
+
+$x = 0
+loop:
+
+print ======== step4
+system sh/exec.sh -n dnode2 -s stop -x SIGINT
+sleep 10000
+system sh/exec.sh -n dnode2 -s start -t
+sleep 10000
+
+print ======== step5
+system sh/exec.sh -n dnode3 -s stop -x SIGINT
+sleep 10000
+system sh/exec.sh -n dnode3 -s start -t
+sleep 10000
+
+print ======== step6
+#sql select count(*) from db.tb1
+#print select count(*) from db.tb1 ==> $data00 $lastRows 
+sql select count(*) from db.tb
+print select count(*) from db.tb ==> $data00 $lastRows 
+if $data00 <= $lastRows then
+  return -1
+endi
+
+print ======== step7
+$lastRows = $data00
+print ======== loop Times $x
+
+if $x < 10 then
+  $x = $x + 1
+  goto loop
+endi
+
+system sh/exec.sh -n dnode1 -s stop  -x SIGINT
+system sh/exec.sh -n dnode2 -s stop  -x SIGINT
+system sh/exec.sh -n dnode3 -s stop  -x SIGINT
+system sh/exec.sh -n dnode4 -s stop  -x SIGINT
+system sh/exec.sh -n dnode5 -s stop  -x SIGINT
+system sh/exec.sh -n dnode6 -s stop  -x SIGINT
+system sh/exec.sh -n dnode7 -s stop  -x SIGINT
+system sh/exec.sh -n dnode8 -s stop  -x SIGINT
\ No newline at end of file