Re: log_buffer 10gr2
- From: Cary Millsap <cary.millsap@xxxxxxxxxxxx>
- To: Ujang Jaenudin <ujang.jaenudin@xxxxxxxxx>
- Date: Thu, 28 May 2009 10:23:53 -0500
Are *log file sync* events eating appreciable time for each transaction?
Have you measured that?
...Or is it that you're concerned about the call count or the total "system
time" being consumed by the calls?
Cary Millsap
Method R Corporation
http://method-r.com
http://carymillsap.blogspot.com
http://twitter.com/cary_millsap
On Thu, May 28, 2009 at 9:49 AM, Ujang Jaenudin <ujang.jaenudin@xxxxxxxxx>wrote:
> I configure it from 4 different LUN + ASM. (2 mirrors of log member).
> this is 2 node RAC and for the connection, a service is set for all
> bea JDBC connection pool to one node only (failover mode).
>
>
> On Thu, May 28, 2009 at 9:43 PM, Johnson, William L (TEIS)
> <WLJohnson@xxxxxxxxxxxxxxxxxxx> wrote:
> > Where are your online redo logs located? Are they using the same disk
> that
> > supports your data files for the database? Many Admins will tell you
> that
> > hardware capabilities will allow you to collocate data files with redo
> logs
> > – but that is not the real world I have seen – even using HP enterprise
> > class disk…
> >
> >
> >
> > ________________________________
> >
> > From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:
> oracle-l-bounce@xxxxxxxxxxxxx]
> > On Behalf Of Bobak, Mark
> > Sent: Thursday, May 28, 2009 10:12 AM
> > To: Cary Millsap; ujang.jaenudin@xxxxxxxxx
> > Cc: Oracle Discussion List
> > Subject: RE: log_buffer 10gr2
> >
> >
> >
> > Cary read my mind. The problem is almost certainly related to commit
> > frequency. Excessive commits will *kill* performance and scalability.
> >
> >
> >
> > From: Cary Millsap [mailto:cary.millsap@xxxxxxxxxxxx]
> > Sent: Thursday, May 28, 2009 10:09 AM
> > To: ujang.jaenudin@xxxxxxxxx
> > Cc: Bobak, Mark; Oracle Discussion List
> > Subject: 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
> > http://twitter.com/cary_millsap
> >
> > 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
> >> --
> >> //www.freelists.org/webpage/oracle-l
> >>
> >>
> >>
> >>
> >>
> > --
> > //www.freelists.org/webpage/oracle-l
> >
> >
>
>
>
> --
> thanks and regards
> ujang | oracle dba | mysql dba
> http://ora62.wordpress.com
>
Other related posts:
