Adaptive Switching Between Log Write Methods can Cause 'log file sync' Waits
Last updated on JANUARY 22, 2018
Applies to:Oracle Database - Enterprise Edition - Version 220.127.116.11 and later
Information in this document applies to any platform.
- The database version is 18.104.22.168
- The log writer process on the database is blocking most of the other sessions and taking an average wait time of 10ms to commit.
- On checking the hardware, the I/O wait time is very small from the hardware side
- This means that all the time is on CPU processing the request.
- Database is OLTP-based and has high commits/second
- The same issue did not occur in 10g.
- The problem seems to 'go away' temporarily after the database is restarted but ultimately returns after a few days.
- AWR may show 'log file sync' waits as the highest wait:
The database was upgraded from 10.2.0.4 to 22.214.171.124.1.
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