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.
Tue Dec 03 16:21:35 2019
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.
Tue Dec 03 16:38:23 2019
Adjusting the default value of parameter parallel_max_servers
from 640 to 320 due to the value of parameter processes (350)
Starting ORACLE instance (normal)
Tue Dec 03 21:09:32 2019
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.
Tue Dec 03 22:00:00 2019
Setting Resource Manager plan SCHEDULER[0x32DA]:DEFAULT_MAINTENANCE_PLAN via scheduler window
Setting Resource Manager plan DEFAULT_MAINTENANCE_PLAN via parameter
Tue Dec 03 22:00:00 2019
Starting background process VKRM
Tue Dec 03 22:00:00 2019
VKRM started with pid=78, OS id=28922
Tue Dec 03 22:00:02 2019
Begin automatic SQL Tuning Advisor run for special tuning task "SYS_AUTO_SQL_TUNING_TASK"
Tue Dec 03 22:20:55 2019
End automatic SQL Tuning Advisor run for special tuning task "SYS_AUTO_SQL_TUNING_TASK"
Tue Dec 03 22:46:17 2019
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.
Wed Dec 04 00:00:29 2019
Thread 1 advanced to log sequence 5843 (LGWR switch)
In Oracle Database 11g in, VKTM is a new background process. The meaning of this process are:
VKTM (virtual keeper of time) is responsible for providing a wall-clock time (updated every second) and
reference-time counter (updated every 20 ms and available only when running at elevated priority).
That is, the process for providing a clock database, updated every second; or as a reference time counter, in this manner are updated every 20 msec, is available only when a high priority.
In the event of abnormal or change the system time, VKTM process will detect these changes, alert the user, especially in the RAC environment, offset and changes over time is likely to cause a system failure. The following is a warning alarm log:
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.
By VKTM process, database and operating system can reduce the interaction, Kamus explanation is:
All Oracle database background or foreground process before 11g If you need to get the current time information, we need to call the operating system gettimeofday () function or a similar function.
The VKTM process is designed to obtain information and the time information is stored for other processes in the SGA, so when other processes requiring time information, just go to a memory location of the SGA to get like,
without frequent calls gettimeofday ()function. No doubt, this will be more efficient.
In the RAC test, Oracle 11.1.0.6 version LMSx the process of acquiring time information, you can probably benefit from a 70% speed boost VKTM process, and 11.1.0.7 will be higher.
At the same time, because the gettimeofday () function also sparked a lot of bug, so it is still NORAC RAC libraries have benefited from VKTM process.
Reference
https://www.eygle.com/archives/2012/06/oracle_11g_vktm.html