AW: RE: log_buffer 10gr2

From: Martin Berger <martin.a.berger@xxxxxxxxx>
To: <Mark.Bobak@xxxxxxxxxxxx>, Cary Millsap <cary.millsap@xxxxxxxxxxxx>, <ujang.jaenudin@xxxxxxxxx>
Date: Thu, 28 May 2009 16:37:50 +0200
If you can not change the commit frequency, maybe tweaking COMMIT_WRITE can 
help? ( at least for a little bit )

Best regards,
 Martin

----- Ursprüngliche Nachricht -----
Von: Bobak, Mark <Mark.Bobak@xxxxxxxxxxxx>
Gesendet: Donnerstag, 28. Mai 2009 16:11
An: Cary Millsap <cary.millsap@xxxxxxxxxxxx>; ujang.jaenudin@xxxxxxxxx 
<ujang.jaenudin@xxxxxxxxx>
Cc: Oracle Discussion List <oracle-l@xxxxxxxxxxxxx>
Betreff: 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: 

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AW: RE: log_buffer 10gr2

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