'control file sequential read' high average time

From: HansP <Hans-Peter.Sloot_at_atosorigin.com>
Date: Mon, 29 Aug 2011 06:18:11 -0700 (PDT)
Message-ID: <a43448ed-a030-4d0b-aeb5-cb89376e2fea_at_19g2000vbv.googlegroups.com>

Db version
Physical standby : LGWR ASYNC
Database on ASM.
Application Oracle EBS
Redo log files : 5 groups with 2 members each 500M Log switches: every 5 minutes

During stress tests with about 2000 users the statistic 'user commits' of v$sysstat shows about 250 commits and rollbacks per second. The average time for 'log file sync' starts to increase until it reaches 490.000 usec per occurence from about 1.000 usec during off peak hours. The
The average time for 'log file parallel write' increases to about 2.200 usec from about 700 usec during off peak hours. When looking in dba_hist_active_sess_history the event that occurs for the log writer process is 'control file sequential read' with about 90% of the total wait time.
During the same time frame the average time for 'control file sequential read' increases to about 13.000 usec from about 45 usec during off peak hours.

I am trying to figure out why there is an about 500 fold increase of the log file sync event.
Could it have to do with the standby?
Is the number of commits per second too high?

Any clues?

Regards HansP Received on Mon Aug 29 2011 - 08:18:11 CDT

Original text of this message