Re: 'control file sequential read' high average time

Is any other process reading the control file ? Is any other process writing to the control file ? Does the event histogram show a normal distribution or a skew Are the rollbacks "user rollbacks" only, or "transaction rollback" as well.

-- 
Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com


"HansP" <Hans-Peter.Sloot_at_atosorigin.com> wrote in message 
news:a43448ed-a030-4d0b-aeb5-cb89376e2fea_at_19g2000vbv.googlegroups.com...


> Db version 11.2.0.2

> 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?