Time drift detected. Please check VKTM trace file for more details

Alert 日志中重复出现如下信息

Time drift detected. Please check VKTM trace file for more details.

 

环境如下

OS VERSION: AIX 6.1 DB VERSION:Oracle RAC 11.2.0.3.0

 

VKTM 的trace file文件内容如下

VKTM running at (10)millisec precision with DBRM quantum (100)ms [Start] HighResTick = 16403562634147 kstmrmtickcnt = 0 : ksudbrmseccnt[0] = 1396607063 kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1041799)usec at (16609084909585) whereas (1000000) is allowed kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1087706)usec at (16691324485199) whereas (1000000) is allowed …….

可以看到并没有什么有用的信息

 

下面是[文档ID 1347586.1]关于该问题的说明

 

Applies to:

Oracle Database - Enterprise Edition -Version 11.2.0.2 and later
Information in this document applies to any platform.

影响的版本 11.2.0.2及更新的版本

该文档中的信息适用于任何平台

Goal

Below message keeps repeating in Alert-log.

Time drift detected. Please check VKTMtrace file for more details.

This note explains the possible cause and if the issue needs to be addressed ornot.

Solution

There are multiple bugs filed for thisissue, Some of them follows:

Bug12601857 - TIME DRIFT DETECTED. PLEASE CHECK VKTMTRACE FILE FOR MORE DETAILS.
Bug 12374867 - TIME DRIFT DETECTED.PLEASE CHECK VKTM TRACE FILE FOR MORE DETAILS.

Which were closed as duplicates of:

Bug 11837095 "TIME DRIFTDETECTED" APPEARS INTERMITTENTLY IN ALERT LOG, THO' EVENT 10795 SET.

 

To fix the issue, please download and applypatch 11837095 as available for your release/platform.

NOTE:
Patch 11837095 extends to functionality of event 10795 (set to level 2)for VKTM tracing and limits alert log entries.

After applying the patch, enable event10975 at level 2:

 

altersystem set event="10795 trace name context forever, level 2"scope=spfile;

 

 Then bounce the instance (shutdonwthen startup) for the event to be applied.

The permanent fix is planned to be includedin the 11.2.0.4 and 12.1 releases.

 

 应用patch 11837095后需要设置event10795 level 2 ，该event需要重启数据库才会生效

，命令如上黑色字体命令。

Oracle计划将在11.2.0.4和12.1中修复这个bug

 

Oracle关于该问题的解释

Meaning and technical Impact of the error: The time drifts usually occurring less than 1sec and 5 sec for forward and backward respectively are permissible and OK. If the traces are emitting time drifts of amount beyond these ranges, then it needs to be analyzed. Most of the times, during high loads, there would be issues with underlying OS due to virtual memory, network time protocol improper configuration etc. In general VKTM process need to be scheduled in every 10ms, if due to above reasons this is not happening we see the time drifts and to certain level (mentioned above) are permissible. Eventually, this probably would cause the resource manager to take improper decisions and can lead to a hang in worst case.