diff --git a/include/os/os.h b/include/os/os.h
index 9e5e9221e4..165563f634 100644
--- a/include/os/os.h
+++ b/include/os/os.h
@@ -129,6 +129,8 @@ extern int64_t          tsRandErrDivisor;
 extern int64_t          tsRandErrScope;
 extern threadlocal bool tsEnableRandErr;
 
+#define TAOS_UNUSED(expr) (void)(expr)
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/os/osEnv.h b/include/os/osEnv.h
index 5f7cdf44dc..f235d3f235 100644
--- a/include/os/osEnv.h
+++ b/include/os/osEnv.h
@@ -55,7 +55,7 @@ extern SDiskSpace tsLogSpace;
 extern SDiskSpace tsTempSpace;
 
 int32_t osDefaultInit();
-void osUpdate();
+int32_t osUpdate();
 void osCleanup();
 
 bool osLogSpaceAvailable();
diff --git a/source/common/src/cos.c b/source/common/src/cos.c
index 82b1fad2ce..88f97a498d 100644
--- a/source/common/src/cos.c
+++ b/source/common/src/cos.c
@@ -1871,7 +1871,6 @@ void s3EvictCache(const char *path, long object_size) {
   taosDirName(dir_name);
 
   if (taosGetDiskSize((char *)dir_name, &disk_size) < 0) {
-    terrno = TAOS_SYSTEM_ERROR(errno);
     vError("failed to get disk:%s size since %s", path, terrstr());
     return;
   }
diff --git a/source/dnode/mgmt/node_mgmt/src/dmEnv.c b/source/dnode/mgmt/node_mgmt/src/dmEnv.c
index 620aed709f..f48ca35330 100644
--- a/source/dnode/mgmt/node_mgmt/src/dmEnv.c
+++ b/source/dnode/mgmt/node_mgmt/src/dmEnv.c
@@ -89,9 +89,13 @@ static bool dmDataSpaceAvailable() {
 }
 
 static int32_t dmCheckDiskSpace() {
-  osUpdate();
   // availability
   int32_t code = 0;
+  code =  osUpdate();
+  if(code != 0) {
+    code = 0; // ignore the error, just log it
+    dError("failed to update os info since %s", tstrerror(code));
+  }
   if (!dmDataSpaceAvailable()) {
     code = TSDB_CODE_NO_DISKSPACE;
     return code;
diff --git a/source/dnode/mgmt/node_mgmt/src/dmNodes.c b/source/dnode/mgmt/node_mgmt/src/dmNodes.c
index 38bd9f6b92..f67901d6d5 100644
--- a/source/dnode/mgmt/node_mgmt/src/dmNodes.c
+++ b/source/dnode/mgmt/node_mgmt/src/dmNodes.c
@@ -159,7 +159,9 @@ int32_t dmRunDnode(SDnode *pDnode) {
     }
 
     if (count == 10) {
-      osUpdate();
+      if(osUpdate() != 0) {
+        dError("failed to update os info");
+      }
       count = 0;
     } else {
       count++;
diff --git a/source/dnode/vnode/src/meta/metaTable.c b/source/dnode/vnode/src/meta/metaTable.c
index 656af563e4..b568b03c2c 100644
--- a/source/dnode/vnode/src/meta/metaTable.c
+++ b/source/dnode/vnode/src/meta/metaTable.c
@@ -232,7 +232,7 @@ int metaDelJsonVarFromIdx(SMeta *pMeta, const SMetaEntry *pCtbEntry, const SSche
         }
         int32_t len = taosUcs4ToMbs((TdUcs4 *)pTagVal->pData, pTagVal->nData, val + VARSTR_HEADER_SIZE);
         if (len < 0) {
-          TAOS_CHECK_GOTO(TSDB_CODE_OUT_OF_MEMORY, NULL, _exception);
+          TAOS_CHECK_GOTO(len, NULL, _exception);
         }
         memcpy(val, (uint16_t *)&len, VARSTR_HEADER_SIZE);
         type = TSDB_DATA_TYPE_VARCHAR;
diff --git a/source/libs/tfs/src/tfsDisk.c b/source/libs/tfs/src/tfsDisk.c
index 07fa8d79b9..35a118baad 100644
--- a/source/libs/tfs/src/tfsDisk.c
+++ b/source/libs/tfs/src/tfsDisk.c
@@ -33,7 +33,7 @@ int32_t tfsNewDisk(int32_t level, int32_t id, int8_t disable, const char *path,
   pDisk->id = id;
   pDisk->disable = disable;
   if (taosGetDiskSize(pDisk->path, &pDisk->size) < 0) {
-    code = TAOS_SYSTEM_ERROR(errno);  // TODO: refactor this line
+    code = terrno;
     TAOS_CHECK_GOTO(code, &lino, _exit);
   }
 _exit:
@@ -57,7 +57,7 @@ STfsDisk *tfsFreeDisk(STfsDisk *pDisk) {
 
 int32_t tfsUpdateDiskSize(STfsDisk *pDisk) {
   if (taosGetDiskSize(pDisk->path, &pDisk->size) < 0) {
-    int32_t code = TAOS_SYSTEM_ERROR(errno);  // TODO: refactor this line
+    int32_t code = terrno;
     fError("failed to get disk:%s size, level:%d id:%d since %s", pDisk->path, pDisk->level, pDisk->id,
            tstrerror(code));
     TAOS_RETURN(code);
diff --git a/source/os/src/osEnv.c b/source/os/src/osEnv.c
index 8334d609b1..c0273e4a6f 100644
--- a/source/os/src/osEnv.c
+++ b/source/os/src/osEnv.c
@@ -94,16 +94,18 @@ int32_t osDefaultInit() {
   return code;
 }
 
-void osUpdate() {
+int32_t osUpdate() {
+  int code = 0;
   if (tsLogDir[0] != 0) {
-    (void)taosGetDiskSize(tsLogDir, &tsLogSpace.size);
+    code = taosGetDiskSize(tsLogDir, &tsLogSpace.size);
   }
   if (tsDataDir[0] != 0) {
-    (void)taosGetDiskSize(tsDataDir, &tsDataSpace.size);
+    code = taosGetDiskSize(tsDataDir, &tsDataSpace.size);
   }
   if (tsTempDir[0] != 0) {
-    (void)taosGetDiskSize(tsTempDir, &tsTempSpace.size);
+    code = taosGetDiskSize(tsTempDir, &tsTempSpace.size);
   }
+  return code;
 }
 
 void osCleanup() {}
diff --git a/source/os/src/osFile.c b/source/os/src/osFile.c
index 94ead5c129..164626299b 100644
--- a/source/os/src/osFile.c
+++ b/source/os/src/osFile.c
@@ -174,9 +174,12 @@ int64_t taosCopyFile(const char *from, const char *to) {
   }
 
   code = taosFsyncFile(pFileTo);
+  if (code != 0) {
+    goto _err;
+  }
 
-  (void)taosCloseFile(&pFileFrom);
-  (void)taosCloseFile(&pFileTo);
+  TAOS_UNUSED(taosCloseFile(&pFileFrom));
+  TAOS_UNUSED(taosCloseFile(&pFileTo));
 
   if (code != 0) {
     terrno = code;
@@ -187,10 +190,10 @@ int64_t taosCopyFile(const char *from, const char *to) {
 
 _err:
 
-  if (pFileFrom != NULL) (void)taosCloseFile(&pFileFrom);
-  if (pFileTo != NULL) (void)taosCloseFile(&pFileTo);
+  if (pFileFrom != NULL) TAOS_UNUSED(taosCloseFile(&pFileFrom));
+  if (pFileTo != NULL) TAOS_UNUSED(taosCloseFile(&pFileTo));
   /* coverity[+retval] */
-  (void)taosRemoveFile(to);
+  TAOS_UNUSED(taosRemoveFile(to));
 
   terrno = code;
   return -1;
@@ -1120,8 +1123,8 @@ int32_t taosCloseFile(TdFilePtr *ppFile) {
   (void)taosThreadRwlockWrlock(&((*ppFile)->rwlock));
 #endif
   if ((*ppFile)->fp != NULL) {
-    (void)fflush((*ppFile)->fp);
-    (void)fclose((*ppFile)->fp);
+    TAOS_UNUSED(fflush((*ppFile)->fp));
+    TAOS_UNUSED(fclose((*ppFile)->fp));
     (*ppFile)->fp = NULL;
   }
 #ifdef WINDOWS
@@ -1471,7 +1474,11 @@ int32_t taosCompressFile(char *srcFileName, char *destFileName) {
   while (!feof(pSrcFile->fp)) {
     len = (int32_t)fread(data, 1, compressSize, pSrcFile->fp);
     if (len > 0) {
-      (void)gzwrite(dstFp, data, len);
+      if(gzwrite(dstFp, data, len) == 0) {
+        terrno = TAOS_SYSTEM_ERROR(errno);
+        ret = terrno;
+        goto cmp_end;
+      }
     }
   }
 
@@ -1481,11 +1488,11 @@ cmp_end:
     (void)close(fd);
   }
   if (pSrcFile) {
-    (void)taosCloseFile(&pSrcFile);
+    TAOS_UNUSED(taosCloseFile(&pSrcFile));
   }
 
   if (dstFp) {
-    (void)gzclose(dstFp);
+    TAOS_UNUSED(gzclose(dstFp));
   }
 
   taosMemoryFree(data);
diff --git a/source/os/src/osString.c b/source/os/src/osString.c
index e2e0c04515..ffc64f3493 100644
--- a/source/os/src/osString.c
+++ b/source/os/src/osString.c
@@ -94,6 +94,8 @@ int32_t taosStr2int64(const char *str, int64_t *val) {
   int64_t ret = strtoll(str, &endptr, 10);
   if (errno == ERANGE && (ret == LLONG_MAX || ret == LLONG_MIN)) {
     return TAOS_SYSTEM_ERROR(errno);
+  } else if (errno == EINVAL && ret == 0) {
+    return TSDB_CODE_INVALID_PARA;
   } else {
     *val = ret;
     return 0;
@@ -106,7 +108,7 @@ int32_t taosStr2int16(const char *str, int16_t *val) {
   if (code) {
     return code;
   } else if (tmp > INT16_MAX || tmp < INT16_MIN) {
-    return TSDB_CODE_INVALID_PARA;
+    return TAOS_SYSTEM_ERROR(ERANGE);
   } else {
     *val = (int16_t)tmp;
     return 0;
@@ -119,7 +121,7 @@ int32_t taosStr2int32(const char *str, int32_t *val) {
   if (code) {
     return code;
   } else if (tmp > INT32_MAX || tmp < INT32_MIN) {
-    return TSDB_CODE_INVALID_PARA;
+    return TAOS_SYSTEM_ERROR(ERANGE);
   } else {
     *val = (int32_t)tmp;
     return 0;
@@ -132,7 +134,7 @@ int32_t taosStr2int8(const char *str, int8_t *val) {
   if (code) {
     return code;
   } else if (tmp > INT8_MAX || tmp < INT8_MIN) {
-    return TSDB_CODE_INVALID_PARA;
+    return TAOS_SYSTEM_ERROR(ERANGE);
   } else {
     *val = (int8_t)tmp;
     return 0;
@@ -336,17 +338,20 @@ bool taosMbsToUcs4(const char *mbs, size_t mbsLength, TdUcs4 *ucs4, int32_t ucs4
 #endif
 }
 
+// if success, return the number of bytes written to mbs ( >= 0)
+// otherwise return error code ( < 0)
 int32_t taosUcs4ToMbs(TdUcs4 *ucs4, int32_t ucs4_max_len, char *mbs) {
 #ifdef DISALLOW_NCHAR_WITHOUT_ICONV
   printf("Nchar cannot be read and written without iconv, please install iconv library and recompile.\n");
-  return -1;
+  terrno = TSDB_CODE_APP_ERROR;
+  return terrno;
 #else
 
   int32_t idx = -1;
   int32_t code = 0;
   iconv_t conv = taosAcquireConv(&idx, C2M);
   if ((iconv_t)-1 == conv || (iconv_t)0 == conv) {
-    return false;
+    return TSDB_CODE_APP_ERROR;
   }
   
   size_t  ucs4_input_len = ucs4_max_len;
@@ -364,10 +369,13 @@ int32_t taosUcs4ToMbs(TdUcs4 *ucs4, int32_t ucs4_max_len, char *mbs) {
 #endif
 }
 
+// if success, return the number of bytes written to mbs ( >= 0)
+// otherwise return error code ( < 0)
 int32_t taosUcs4ToMbsEx(TdUcs4 *ucs4, int32_t ucs4_max_len, char *mbs, iconv_t conv) {
 #ifdef DISALLOW_NCHAR_WITHOUT_ICONV
   printf("Nchar cannot be read and written without iconv, please install iconv library and recompile.\n");
-  return -1;
+  terrno = TSDB_CODE_APP_ERROR;
+  return terrno;
 #else
 
   size_t ucs4_input_len = ucs4_max_len;
@@ -384,7 +392,8 @@ int32_t taosUcs4ToMbsEx(TdUcs4 *ucs4, int32_t ucs4_max_len, char *mbs, iconv_t c
 bool taosValidateEncodec(const char *encodec) {
 #ifdef DISALLOW_NCHAR_WITHOUT_ICONV
   printf("Nchar cannot be read and written without iconv, please install iconv library and recompile.\n");
-  return true;
+  terrno = TSDB_CODE_APP_ERROR;
+  return false;
 #else
   iconv_t cd = iconv_open(encodec, DEFAULT_UNICODE_ENCODEC);
   if (cd == (iconv_t)(-1)) {
diff --git a/source/os/src/osSysinfo.c b/source/os/src/osSysinfo.c
index 137bb8f0db..93fa9fa222 100644
--- a/source/os/src/osSysinfo.c
+++ b/source/os/src/osSysinfo.c
@@ -779,15 +779,15 @@ int32_t taosGetDiskSize(char *dataDir, SDiskSize *diskSize) {
     return 0;
   } else {
     // printf("failed to get disk size, dataDir:%s errno:%s", tsDataDir, strerror(errno));
-    // terrno = TAOS_SYSTEM_ERROR(errno);
-    return -1;
+    terrno = TAOS_SYSTEM_WINAPI_ERROR(GetLastError());
+    return terrno;
   }
 #elif defined(_TD_DARWIN_64)
   struct statvfs info;
   if (statvfs(dataDir, &info)) {
     // printf("failed to get disk size, dataDir:%s errno:%s", tsDataDir, strerror(errno));
-    // terrno = TAOS_SYSTEM_ERROR(errno);
-    return -1;
+    terrno = TAOS_SYSTEM_ERROR(errno);
+    return terrno;
   } else {
     diskSize->total = info.f_blocks * info.f_frsize;
     diskSize->avail = info.f_bavail * info.f_frsize;
diff --git a/source/util/src/tlog.c b/source/util/src/tlog.c
index bde3d48a6d..bd22a4e42b 100644
--- a/source/util/src/tlog.c
+++ b/source/util/src/tlog.c
@@ -215,7 +215,7 @@ int32_t taosInitSlowLog() {
 
 int32_t taosInitLog(const char *logName, int32_t maxFiles, bool tsc) {
   if (atomic_val_compare_exchange_8(&tsLogInited, 0, 1) != 0) return 0;
-  osUpdate();
+  TAOS_CHECK_RETURN(osUpdate());
 
   TAOS_CHECK_RETURN(taosInitNormalLog(logName, maxFiles));
   if (tsc){
@@ -908,7 +908,7 @@ static void *taosAsyncOutputLog(void *param) {
     updateCron++;
     taosMsleep(writeInterval);
     if (count > 1000) {
-      osUpdate();
+      TAOS_UNUSED(osUpdate());
       count = 0;
     }