ALERT 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.


Cause
This problem is due to the Bug 11837095 - "TIME DRIFT DETECTED" APPEARS INTERMITTENTLY IN ALERT LOG"


Solution
Time drift" error is a " message which can be ignored, to remove the "Warning: VKTM detected set event 10795 or Apply patch 11837095


SQL> alter system set event="10795 trace name context forever, level 2" scope=spfile;