vktm进程的作用

用作时钟同步
告警日志：

Mon Jun 05 03:21:34 2023
Archived Log entry 299909 added for thread 1 sequence 264886 ID 0xc592e7f1 dest 1:
Mon Jun 05 04:30:09 2023
Warning: VKTM detected a time drift.
Time drifts can result in an unexpected behavior such as time-outs. Please check trace file for more details.
Mon Jun 05 07:02:40 2023
Thread 1 advanced to log sequence 264888 (LGWR switch)

检查
opatch lspatches
opatch lsinv
ps -ef|grep vktm
检查对应的trc文件

kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1629825)usec at (1679419809628257) whereas (1000000) is allowed
kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1621553)usec at (1679518809738055) whereas (1000000) is allowed
kstmchkdrift (kstmhighrestimecntkeeper:highres): Time jumped forward by (1673370)usec at (1680073209770025) whereas (1000000) is allowed

确认运行模式
ps -ef|grep ntp
ps -ef|grep octss

[grid]$ crsctl check ctss

CRS-4701: The Cluster Time Synchronization Service is in Active mode.
CRS-4702: Offset (in msec): 0

如果向前和向后的时间漂移分别小于1秒和5秒，则允许且OK。

如果跟踪信号发出的时间漂移超过了这些范围，那么就需要对其进行分析。

大多数情况下，在高负载期间，由于虚拟内存，网络时间协议配置不当等原因，底层操作系统会出现问题。

一般情况下，VKTM进程需要每10毫秒调度一次，如果由于上述原因没有发生这种情况，发生时间少于1秒和5秒，则允许。

{BANNED}最佳终，这可能会导致资源管理器做出不正确的决策，并在{BANNED}最佳坏的情况下导致挂起。

如果是asm实例的告警日志报告

Mon May 12 02:45:15 2014
Warning: VKTM detected a time drift.
Time drifts can result in an unexpected behavior such as time-outs. Please check trace file for more details.

那么就是bug

alter system set event="10795 trace name context forever, level 2" scope=spfile;
重启asm实例

参考：

ASM Instance Is Reporting “Warning: VKTM detected a time drift” (Doc ID 1678120.1)