diff --git a/docs/zh/17-operation/03-tolerance.md b/docs/zh/17-operation/03-tolerance.md
index 2cfd4b6484acdcb617cd91ed694d2f4c0f010e93..1ce485b042d6900ccc1c1bc3bcb6779e14b776ff 100644
--- a/docs/zh/17-operation/03-tolerance.md
+++ b/docs/zh/17-operation/03-tolerance.md
@@ -26,5 +26,3 @@ TDengine 集群中的时序数据的副本数是与数据库关联的，一个
 TDengine 集群的节点数必须大于等于副本数，否则创建表时将报错。
 
 当 TDengine 集群中的节点部署在不同的物理机上，并设置多个副本数时，就实现了系统的高可靠性，无需再使用其他软件或工具。TDengine 企业版还可以将副本部署在不同机房，从而实现异地容灾。
-
-另外一种灾备方式是通过 `taosX` 将一个 TDengine 集群的数据同步复制到物理上位于不同数据中心的另一个 TDengine 集群。其详细使用方法请参考 [taosX 参考手册](../../reference/taosX)
diff --git a/include/libs/sync/sync.h b/include/libs/sync/sync.h
index 790cbf906da887c01bec011a875a67db8f359b7b..e6a4dd1d493969a333005a64f515ba35dde34573 100644
--- a/include/libs/sync/sync.h
+++ b/include/libs/sync/sync.h
@@ -33,7 +33,7 @@ extern bool gRaftDetailLog;
 #define SYNC_MAX_READ_RANGE          2
 #define SYNC_MAX_PROGRESS_WAIT_MS    4000
 #define SYNC_MAX_START_TIME_RANGE_MS (1000 * 20)
-#define SYNC_MAX_RECV_TIME_RANGE_MS  1000
+#define SYNC_MAX_RECV_TIME_RANGE_MS  1200
 #define SYNC_ADD_QUORUM_COUNT        3
 
 #define SYNC_MAX_BATCH_SIZE 1
diff --git a/source/common/src/tglobal.c b/source/common/src/tglobal.c
index c763bbed9c470d9527877a7cfb2312efdc8d612a..adc5af1a17cf7a66c673c61e031a35ea3a968d38 100644
--- a/source/common/src/tglobal.c
+++ b/source/common/src/tglobal.c
@@ -75,7 +75,7 @@ int32_t  tsMonitorMaxLogs = 100;
 bool     tsMonitorComp = false;
 
 // telem
-bool     tsEnableTelem = false;
+bool     tsEnableTelem = true;
 int32_t  tsTelemInterval = 86400;
 char     tsTelemServer[TSDB_FQDN_LEN] = "telemetry.taosdata.com";
 uint16_t tsTelemPort = 80;
@@ -166,7 +166,7 @@ int32_t tsTtlPushInterval = 86400;
 int32_t tsGrantHBInterval = 60;
 
 #ifndef _STORAGE
-int32_t taosSetTfsCfg(SConfig *pCfg) { 
+int32_t taosSetTfsCfg(SConfig *pCfg) {
   SConfigItem *pItem = cfgGetItem(pCfg, "dataDir");
   memset(tsDataDir, 0, PATH_MAX);
 
@@ -180,7 +180,7 @@ int32_t taosSetTfsCfg(SConfig *pCfg) {
     uError("failed to create dataDir:%s", tsDataDir);
     return -1;
   }
-  return 0; 
+  return 0;
 }
 #else
 int32_t taosSetTfsCfg(SConfig *pCfg);
diff --git a/source/libs/function/src/builtinsimpl.c b/source/libs/function/src/builtinsimpl.c
index 5aeaecd59867fba87439fb6951e1ed548323856e..bf4a07f8e2c110c88ec3fe79b2fba557123fa7ab 100644
--- a/source/libs/function/src/builtinsimpl.c
+++ b/source/libs/function/src/builtinsimpl.c
@@ -3970,16 +3970,16 @@ int32_t elapsedFunction(SqlFunctionCtx* pCtx) {
     TSKEY*  ptsList = (int64_t*)colDataGetData(pCol, 0);
     if (pCtx->order == TSDB_ORDER_DESC) {
       if (pCtx->start.key == INT64_MIN) {
-        pInfo->max =
-            (pInfo->max < ptsList[start + pInput->numOfRows - 1]) ? ptsList[start + pInput->numOfRows - 1] : pInfo->max;
+        pInfo->max = (pInfo->max < ptsList[start]) ? ptsList[start] : pInfo->max;
       } else {
         pInfo->max = pCtx->start.key + 1;
       }
 
-      if (pCtx->end.key != INT64_MIN) {
-        pInfo->min = pCtx->end.key;
+      if (pCtx->end.key == INT64_MIN) {
+        pInfo->min = (pInfo->min > ptsList[start + pInput->numOfRows - 1]) ?
+                     ptsList[start + pInput->numOfRows - 1] : pInfo->min;
       } else {
-        pInfo->min = ptsList[start];
+        pInfo->min = pCtx->end.key;
       }
     } else {
       if (pCtx->start.key == INT64_MIN) {
@@ -3988,10 +3988,11 @@ int32_t elapsedFunction(SqlFunctionCtx* pCtx) {
         pInfo->min = pCtx->start.key;
       }
 
-      if (pCtx->end.key != INT64_MIN) {
-        pInfo->max = pCtx->end.key + 1;
+      if (pCtx->end.key == INT64_MIN) {
+        pInfo->max = (pInfo->max < ptsList[start + pInput->numOfRows - 1]) ?
+                     ptsList[start + pInput->numOfRows - 1] : pInfo->max;
       } else {
-        pInfo->max = ptsList[start + pInput->numOfRows - 1];
+        pInfo->max = pCtx->end.key + 1;
       }
     }
   }
diff --git a/source/libs/transport/inc/transComm.h b/source/libs/transport/inc/transComm.h
index 6b52c7427177bdd1662db63d57308e231348e99b..bc1c6386f6e0d9a61b21e5ca0e3aa198c1da043e 100644
--- a/source/libs/transport/inc/transComm.h
+++ b/source/libs/transport/inc/transComm.h
@@ -98,6 +98,11 @@ typedef void* queue[2];
 #define TRANS_RETRY_INTERVAL    15    // retry interval (ms)
 #define TRANS_CONN_TIMEOUT      3     // connect timeout (s)
 #define TRANS_READ_TIMEOUT      3000  // read timeout  (ms)
+#define TRANS_PACKET_LIMIT      1024 * 1024 * 512
+
+#define TRANS_MAGIC_NUM 0x5f375a86
+
+#define TRANS_NOVALID_PACKET(src) ((src) != TRANS_MAGIC_NUM ? 1 : 0)
 
 typedef SRpcMsg      STransMsg;
 typedef SRpcCtx      STransCtx;
@@ -151,6 +156,7 @@ typedef struct {
   char hasEpSet : 2;  // contain epset or not, 0(default): no epset, 1: contain epset
 
   char     user[TSDB_UNI_LEN];
+  uint32_t magicNum;
   STraceId traceId;
   uint64_t ahandle;  // ahandle assigned by client
   uint32_t code;     // del later
@@ -203,6 +209,7 @@ typedef struct SConnBuffer {
   int   cap;
   int   left;
   int   total;
+  int   invalid;
 } SConnBuffer;
 
 typedef void (*AsyncCB)(uv_async_t* handle);
diff --git a/source/libs/transport/src/thttp.c b/source/libs/transport/src/thttp.c
index 62277a7569a836f84e2ea143dc648737c208b3c8..4e49e9ca13a7924e43dc106ec9b495b4d8fa4015 100644
--- a/source/libs/transport/src/thttp.c
+++ b/source/libs/transport/src/thttp.c
@@ -14,15 +14,22 @@
  */
 
 #define _DEFAULT_SOURCE
-#ifdef USE_UV
-#include <uv.h>
-#endif
 // clang-format off
+#include <uv.h>
 #include "zlib.h"
 #include "thttp.h"
 #include "taoserror.h"
 #include "tlog.h"
 
+typedef struct SHttpClient {
+  uv_connect_t conn;
+  uv_tcp_t     tcp;
+  uv_write_t   req;
+  uv_buf_t*    buf;
+  char*        addr;
+  uint16_t     port;
+} SHttpClient;
+
 static int32_t taosBuildHttpHeader(const char* server, int32_t contLen, char* pHead, int32_t headLen,
                                    EHttpCompFlag flag) {
   if (flag == HTTP_FLAT) {
@@ -45,7 +52,7 @@ static int32_t taosBuildHttpHeader(const char* server, int32_t contLen, char* pH
   }
 }
 
-int32_t taosCompressHttpRport(char* pSrc, int32_t srcLen) {
+static int32_t taosCompressHttpRport(char* pSrc, int32_t srcLen) {
   int32_t code = -1;
   int32_t destLen = srcLen;
   void*   pDest = taosMemoryMalloc(destLen);
@@ -114,84 +121,53 @@ _OVER:
   return code;
 }
 
-#ifdef USE_UV
+static void destroyHttpClient(SHttpClient* cli) {
+  taosMemoryFree(cli->buf);
+  taosMemoryFree(cli->addr);
+  taosMemoryFree(cli);
+}
+static void clientCloseCb(uv_handle_t* handle) {
+  SHttpClient* cli = handle->data;
+  destroyHttpClient(cli);
+}
+static void clientSentCb(uv_write_t* req, int32_t status) {
+  SHttpClient* cli = req->data;
+  if (status != 0) {
+    terrno = TAOS_SYSTEM_ERROR(status);
+    uError("http-report failed to send data %s", uv_strerror(status));
+  } else {
+    uInfo("http-report succ to send data");
+  }
+  uv_close((uv_handle_t*)&cli->tcp, clientCloseCb);
+}
 static void clientConnCb(uv_connect_t* req, int32_t status) {
-  if (status < 0) {
+  SHttpClient* cli = req->data;
+  if (status != 0) {
     terrno = TAOS_SYSTEM_ERROR(status);
-    uError("connection error %s", uv_strerror(status));
-    uv_close((uv_handle_t*)req->handle, NULL);
+    uError("http-report failed to conn to server, reason:%s, dst:%s:%d", uv_strerror(status), cli->addr, cli->port);
+    uv_close((uv_handle_t*)&cli->tcp, clientCloseCb);
     return;
   }
-  uv_buf_t* wb = req->data;
-  assert(wb != NULL);
-  uv_write_t write_req;
-  uv_write(&write_req, req->handle, wb, 2, NULL);
-  uv_close((uv_handle_t*)req->handle, NULL);
+  uv_write(&cli->req, (uv_stream_t*)&cli->tcp, cli->buf, 2, clientSentCb);
 }
 
-int32_t taosSendHttpReport(const char* server, uint16_t port, char* pCont, int32_t contLen, EHttpCompFlag flag) {
-  uint32_t ipv4 = taosGetIpv4FromFqdn(server);
-  if (ipv4 == 0xffffffff) {
+static int32_t taosBuildDstAddr(const char* server, uint16_t port, struct sockaddr_in* dest) {
+  uint32_t ip = taosGetIpv4FromFqdn(server);
+  if (ip == 0xffffffff) {
     terrno = TAOS_SYSTEM_ERROR(errno);
-    uError("failed to get http server:%s ip since %s", server, terrstr());
+    uError("http-report failed to get http server:%s ip since %s", server, terrstr());
     return -1;
   }
-
-  char ipv4Buf[128] = {0};
-  tinet_ntoa(ipv4Buf, ipv4);
-
-  struct sockaddr_in dest = {0};
-  uv_ip4_addr(ipv4Buf, port, &dest);
-
-  uv_tcp_t   socket_tcp = {0};
-  uv_loop_t* loop = uv_default_loop();
-  uv_tcp_init(loop, &socket_tcp);
-  uv_connect_t* connect = (uv_connect_t*)taosMemoryMalloc(sizeof(uv_connect_t));
-
-  if (flag == HTTP_GZIP) {
-    int32_t dstLen = taosCompressHttpRport(pCont, contLen);
-    if (dstLen > 0) {
-      contLen = dstLen;
-    } else {
-      flag = HTTP_FLAT;
-    }
-  }
-
-  char    header[1024] = {0};
-  int32_t headLen = taosBuildHttpHeader(server, contLen, header, sizeof(header), flag);
-
-  uv_buf_t wb[2];
-  wb[0] = uv_buf_init((char*)header, headLen);
-  wb[1] = uv_buf_init((char*)pCont, contLen);
-
-  connect->data = wb;
-  terrno = 0;
-  uv_tcp_connect(connect, &socket_tcp, (const struct sockaddr*)&dest, clientConnCb);
-  uv_run(loop, UV_RUN_DEFAULT);
-  uv_loop_close(loop);
-  taosMemoryFree(connect);
-  return terrno;
+  char buf[128] = {0};
+  tinet_ntoa(buf, ip);
+  uv_ip4_addr(buf, port, dest);
+  return 0;
 }
-
-#else
 int32_t taosSendHttpReport(const char* server, uint16_t port, char* pCont, int32_t contLen, EHttpCompFlag flag) {
-  int32_t     code = -1;
-  TdSocketPtr pSocket = NULL;
-
-  uint32_t ip = taosGetIpv4FromFqdn(server);
-  if (ip == 0xffffffff) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
-    uError("failed to get http server:%s ip since %s", server, terrstr());
-    goto SEND_OVER;
-  }
-
-  pSocket = taosOpenTcpClientSocket(ip, port, 0);
-  if (pSocket == NULL) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
-    uError("failed to create http socket to %s:%u since %s", server, port, terrstr());
-    goto SEND_OVER;
+  struct sockaddr_in dest = {0};
+  if (taosBuildDstAddr(server, port, &dest) < 0) {
+    return -1;
   }
-
   if (flag == HTTP_GZIP) {
     int32_t dstLen = taosCompressHttpRport(pCont, contLen);
     if (dstLen > 0) {
@@ -200,37 +176,38 @@ int32_t taosSendHttpReport(const char* server, uint16_t port, char* pCont, int32
       flag = HTTP_FLAT;
     }
   }
+  terrno = 0;
 
-  char    header[1024] = {0};
+  char    header[2048] = {0};
   int32_t headLen = taosBuildHttpHeader(server, contLen, header, sizeof(header), flag);
-  if (taosWriteMsg(pSocket, header, headLen) < 0) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
-    uError("failed to send http header to %s:%u since %s", server, port, terrstr());
-    goto SEND_OVER;
-  }
 
-  if (taosWriteMsg(pSocket, (void*)pCont, contLen) < 0) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
-    uError("failed to send http content to %s:%u since %s", server, port, terrstr());
-    goto SEND_OVER;
-  }
+  uv_buf_t* wb = taosMemoryCalloc(2, sizeof(uv_buf_t));
+  wb[0] = uv_buf_init((char*)header, headLen);  // stack var
+  wb[1] = uv_buf_init((char*)pCont, contLen);   //  heap var
 
-  // read something to avoid nginx error 499
-  if (taosWriteMsg(pSocket, header, 10) < 0) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
-    uError("failed to receive response from %s:%u since %s", server, port, terrstr());
-    goto SEND_OVER;
-  }
+  SHttpClient* cli = taosMemoryCalloc(1, sizeof(SHttpClient));
+  cli->conn.data = cli;
+  cli->tcp.data = cli;
+  cli->req.data = cli;
+  cli->buf = wb;
+  cli->addr = tstrdup(server);
+  cli->port = port;
+
+  uv_loop_t* loop = uv_default_loop();
+  uv_tcp_init(loop, &cli->tcp);
+  // set up timeout to avoid stuck;
+  int32_t fd = taosCreateSocketWithTimeout(5);
+  uv_tcp_open((uv_tcp_t*)&cli->tcp, fd);
 
-  code = 0;
 
-SEND_OVER:
-  if (pSocket != NULL) {
-    taosCloseSocket(&pSocket);
+  int32_t ret = uv_tcp_connect(&cli->conn, &cli->tcp, (const struct sockaddr*)&dest, clientConnCb);
+  if (ret != 0) {
+    uError("http-report failed to connect to server, reason:%s, dst:%s:%d", uv_strerror(ret), cli->addr, cli->port);
+    destroyHttpClient(cli);
   }
 
-  return code;
+  uv_run(loop, UV_RUN_DEFAULT);
+  uv_loop_close(loop);
+  return terrno;
 }
-
 // clang-format on
-#endif
diff --git a/source/libs/transport/src/transCli.c b/source/libs/transport/src/transCli.c
index add007e14d2a49a18bb2be13deb17430eb8841c6..8fdfcd5309c927e4e49386340fbd44496a4a7688 100644
--- a/source/libs/transport/src/transCli.c
+++ b/source/libs/transport/src/transCli.c
@@ -759,6 +759,7 @@ void cliSend(SCliConn* pConn) {
   pHead->release = REQUEST_RELEASE_HANDLE(pCliMsg) ? 1 : 0;
   memcpy(pHead->user, pTransInst->user, strlen(pTransInst->user));
   pHead->traceId = pMsg->info.traceId;
+  pHead->magicNum = htonl(TRANS_MAGIC_NUM);
 
   uv_buf_t wb = uv_buf_init((char*)pHead, msgLen);
 
diff --git a/source/libs/transport/src/transComm.c b/source/libs/transport/src/transComm.c
index 4272ec0b1c201d930e4c63c9266312a77bef97bd..3ba8186e9dbebb52260eeb24766de603f957a9e3 100644
--- a/source/libs/transport/src/transComm.c
+++ b/source/libs/transport/src/transComm.c
@@ -91,6 +91,7 @@ int transInitBuffer(SConnBuffer* buf) {
   buf->left = -1;
   buf->len = 0;
   buf->total = 0;
+  buf->invalid = 0;
   return 0;
 }
 int transDestroyBuffer(SConnBuffer* p) {
@@ -108,19 +109,25 @@ int transClearBuffer(SConnBuffer* buf) {
   p->left = -1;
   p->len = 0;
   p->total = 0;
+  p->invalid = 0;
   return 0;
 }
 
 int transDumpFromBuffer(SConnBuffer* connBuf, char** buf) {
+  static const int HEADSIZE = sizeof(STransMsgHead);
+
   SConnBuffer* p = connBuf;
   if (p->left != 0) {
     return -1;
   }
   int total = connBuf->total;
-  *buf = taosMemoryCalloc(1, total);
-  memcpy(*buf, p->buf, total);
-
-  transResetBuffer(connBuf);
+  if (total >= HEADSIZE && !p->invalid) {
+    *buf = taosMemoryCalloc(1, total);
+    memcpy(*buf, p->buf, total);
+    transResetBuffer(connBuf);
+  } else {
+    total = -1;
+  }
   return total;
 }
 
@@ -173,6 +180,7 @@ bool transReadComplete(SConnBuffer* connBuf) {
       memcpy((char*)&head, connBuf->buf, sizeof(head));
       int32_t msgLen = (int32_t)htonl(head.msgLen);
       p->total = msgLen;
+      p->invalid = TRANS_NOVALID_PACKET(htonl(head.magicNum));
     }
     if (p->total >= p->len) {
       p->left = p->total - p->len;
@@ -180,7 +188,8 @@ bool transReadComplete(SConnBuffer* connBuf) {
       p->left = 0;
     }
   }
-  return p->left == 0 ? true : false;
+
+  return (p->left == 0 || p->invalid) ? true : false;
 }
 
 int transSetConnOption(uv_tcp_t* stream) {
diff --git a/source/libs/transport/src/transSvr.c b/source/libs/transport/src/transSvr.c
index 3512b27bf86f71c34562f7bc928d4ecd18807684..c980b70abddd570e63d424842205e5147e2ae31f 100644
--- a/source/libs/transport/src/transSvr.c
+++ b/source/libs/transport/src/transSvr.c
@@ -183,11 +183,15 @@ static void uvHandleActivityTimeout(uv_timer_t* handle) {
   tDebug("%p timeout since no activity", conn);
 }
 
-static void uvHandleReq(SSvrConn* pConn) {
-  STransMsgHead* msg = NULL;
-  int            msgLen = 0;
+static bool uvHandleReq(SSvrConn* pConn) {
+  STrans* pTransInst = pConn->pTransInst;
 
-  msgLen = transDumpFromBuffer(&pConn->readBuf, (char**)&msg);
+  STransMsgHead* msg = NULL;
+  int            msgLen = transDumpFromBuffer(&pConn->readBuf, (char**)&msg);
+  if (msgLen <= 0) {
+    tError("%s conn %p read invalid packet", transLabel(pTransInst), pConn);
+    return false;
+  }
 
   STransMsgHead* pHead = (STransMsgHead*)msg;
   pHead->code = htonl(pHead->code);
@@ -200,9 +204,8 @@ static void uvHandleReq(SSvrConn* pConn) {
   //  uv_read_stop((uv_stream_t*)pConn->pTcp);
   //  transRefSrvHandle(pConn);
   //  uv_queue_work(((SWorkThrd*)pConn->hostThrd)->loop, wreq, uvWorkDoTask, uvWorkAfterTask);
-
   if (uvRecvReleaseReq(pConn, pHead)) {
-    return;
+    return true;
   }
 
   STransMsg transMsg;
@@ -220,7 +223,6 @@ static void uvHandleReq(SSvrConn* pConn) {
       tDebug("conn %p acquired by server app", pConn);
     }
   }
-  STrans*   pTransInst = pConn->pTransInst;
   STraceId* trace = &pHead->traceId;
   if (pConn->status == ConnNormal && pHead->noResp == 0) {
     transRefSrvHandle(pConn);
@@ -258,21 +260,31 @@ static void uvHandleReq(SSvrConn* pConn) {
   transReleaseExHandle(transGetRefMgt(), pConn->refId);
 
   (*pTransInst->cfp)(pTransInst->parent, &transMsg, NULL);
+  return true;
 }
 
 void uvOnRecvCb(uv_stream_t* cli, ssize_t nread, const uv_buf_t* buf) {
-  // opt
-  SSvrConn*    conn = cli->data;
+  SSvrConn* conn = cli->data;
+  STrans*   pTransInst = conn->pTransInst;
+
   SConnBuffer* pBuf = &conn->readBuf;
-  STrans*      pTransInst = conn->pTransInst;
   if (nread > 0) {
     pBuf->len += nread;
     tTrace("%s conn %p total read:%d, current read:%d", transLabel(pTransInst), conn, pBuf->len, (int)nread);
-    while (transReadComplete(pBuf)) {
-      tTrace("%s conn %p alread read complete packet", transLabel(pTransInst), conn);
-      uvHandleReq(conn);
+    if (pBuf->len <= TRANS_PACKET_LIMIT) {
+      while (transReadComplete(pBuf)) {
+        tTrace("%s conn %p alread read complete packet", transLabel(pTransInst), conn);
+        if (uvHandleReq(conn) == false) {
+          destroyConn(conn, true);
+          return;
+        }
+      }
+      return;
+    } else {
+      tError("%s conn %p read unexpected packet, exceed limit", transLabel(pTransInst), conn);
+      destroyConn(conn, true);
+      return;
     }
-    return;
   }
   if (nread == 0) {
     return;
@@ -364,6 +376,7 @@ static void uvPrepareSendData(SSvrMsg* smsg, uv_buf_t* wb) {
   pHead->ahandle = (uint64_t)pMsg->info.ahandle;
   pHead->traceId = pMsg->info.traceId;
   pHead->hasEpSet = pMsg->info.hasEpSet;
+  pHead->magicNum = htonl(TRANS_MAGIC_NUM);
 
   if (pConn->status == ConnNormal) {
     pHead->msgType = (0 == pMsg->msgType ? pConn->inType + 1 : pMsg->msgType);