Re: 'control file sequential read' high average time
From: HansP <Hans-Peter.Sloot_at_atosorigin.com>
Date: Tue, 30 Aug 2011 01:42:06 -0700 (PDT)
Message-ID: <bdcb795a-1b7f-4377-a4a2-9ef13da6db1e_at_a12g2000yqi.googlegroups.com>
On 30 aug, 00:24, "Jonathan Lewis" <jonat..._at_jlcomp.demon.co.uk> wrote:
> 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 Lewishttp://jonathanlewis.wordpress.com
>
On 30 aug, 00:24, "Jonathan Lewis" <jonat..._at_jlcomp.demon.co.uk> wrote:
> 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.
>
Yes other proceses are reading the controlfile. When looking in dba_his_active_sess_history I see that an OMS from GridControl is doing slightly more reads than the LGWR. In 3rd place is the CKPT background process.
Date: Tue, 30 Aug 2011 01:42:06 -0700 (PDT)
Message-ID: <bdcb795a-1b7f-4377-a4a2-9ef13da6db1e_at_a12g2000yqi.googlegroups.com>
On 30 aug, 00:24, "Jonathan Lewis" <jonat..._at_jlcomp.demon.co.uk> wrote:
> 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 Lewishttp://jonathanlewis.wordpress.com
>
On 30 aug, 00:24, "Jonathan Lewis" <jonat..._at_jlcomp.demon.co.uk> wrote:
> 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.
>
Yes other proceses are reading the controlfile. When looking in dba_his_active_sess_history I see that an OMS from GridControl is doing slightly more reads than the LGWR. In 3rd place is the CKPT background process.
Writing to the controlfile is done mainly by the CKPT process. Some other processes (5) are writing too but the number of writes is very low (< 2% of the total number).
In my opinion the event histograms is skewed.
snap_id begin_interval_time wait_time_milli count 974 2011-08-25 16:49:57 1 9723 974 2011-08-25 16:49:57 2 7345 974 2011-08-25 16:49:57 4 5779 974 2011-08-25 16:49:57 8 5339 974 2011-08-25 16:49:57 16 6097 974 2011-08-25 16:49:57 32 6297 974 2011-08-25 16:49:57 64 6205 974 2011-08-25 16:49:57 128 4509 974 2011-08-25 16:49:57 256 2746 974 2011-08-25 16:49:57 512 1128 974 2011-08-25 16:49:57 1024 884 974 2011-08-25 16:49:57 2048 1293 974 2011-08-25 16:49:57 4096 3052 974 2011-08-25 16:49:57 8192 2662
What do you mean with your last question?
regards HansP Received on Tue Aug 30 2011 - 03:42:06 CDT