Re: log_buffer 10gr2

Does the application *need* to be committing as often as it does?

Cary Millsap
Method R Corporation
http://method-r.com
http://carymillsap.blogspot.com
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On Thu, May 28, 2009 at 8:55 AM, Ujang Jaenudin <ujang.jaenudin@xxxxxxxxx>wrote:

> bobak,
>
> log file sync is the main reason.
> _log_io_size is 0 (default??)
>
> strength on my db when user session only 200 but log file sync can
> reach 800 session waitings (from dbconsole). when checking the io log
> file parallel write max is 4ms, but log file sync can reach 22ms.
>
> average redo blocks per write is 13 which means average buffer to
> write to redolog buffer is only 6656 nytes.
>
> yes the application is heavily commit activites (now in the "load
> testing" stage)
>
> any direction why too many spikes (strange) on log file sync?
>
> --
> thanks and regards
> ujang | oracle dba | mysql dba
> http://ora62.wordpress.com
>
>
> On Thu, May 28, 2009 at 8:49 PM, Bobak, Mark <Mark.Bobak@xxxxxxxxxxxx>
> wrote:
> > Ok, first, take a step back.
> >
> > What is motivating you to look at log_buffer in the first place?  Why do
> you think it needs to be adjusted?  Starting w/ 10g, the log_buffer is
> maintained by Oracle, and should not need to be adjusted.  (See MetaLink Doc
> ID 351857.1.)  What is the current value of _log_io_size?  Why do you think
> you need to adjust it?
> >
> > Main question:
> > What is it that is leading you to believe that log_buffer and
> _log_io_size need to be adjusted?
> >
> > -Mark
> >
> > -----Original Message-----
> > From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:
> oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Ujang Jaenudin
> > Sent: Thursday, May 28, 2009 6:14 AM
> > To: Oracle Discussion List
> > Subject: log_buffer 10gr2
> >
> > dear all,
> >
> > I have 10.2.0.3 on solaris sparc,
> > when trying to decrease log_buffer, it could not be done.
> >
> > always keep 14MB, sga is 3.5GB
> > I want to decrease it to 1MB
> >
> > according to metalink note. 351857.1
> > it is expected behavior.
> >
> > so, is it save to change _log_io_size to 1MB ?
> >
> >
> > --
> > thanks and regards
> > ujang | oracle dba | mysql dba
> > http://ora62.wordpress.com
> > --
> > http://www.freelists.org/webpage/oracle-l
> >
> >
> >
> >
> >
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>

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