RE: 10g Automatic Checkpoint Tuning

From: Bobak, Mark <Mark.Bobak_at_il.proquest.com>
Date: Mon, 25 Jun 2007 17:56:14 -0400
Message-ID: <AA29A27627F842409E1D18FB19CDCF270C9B72E3@AABO-EXCHANGE02.bos.il.pqe>

Just a guess....

Are you using buffered filesystems and RAID-5 storage? Stop doing that....especially for the on-line redo log!

-Mark

Mark J. Bobak
Senior Oracle Database Administrator, System & Product Technologies ProQuest
789 E. Eisenhower, Parkway, P.O. Box 1346 Ann Arbor MI 48106-1346
734.997.4059 or 800.521.0600 x 4059
mark.bobak_at_il.proquest.com
www.proquest.com
www.csa.com

ProQuest...Start here.

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Raj Mareddi Sent: Monday, June 25, 2007 5:10 PM
To: oracle-l
Subject: 10g Automatic Checkpoint Tuning

Guys,

The following are the top-4 waits after CPU Time in my AWR reports during a batch window.

log file switch (checkpoint incomplete)
free buffer waits
log file switch (private strand flush incomplete) log file parallel write

Just realized that log switches are happening very frequent.. each log member is 300M and 3 groups. this size seems to be okay.. other database has 100M member and the same batch job runs good there. First wait says, checkpoint incomplete.. I have started looking at checkpoint tuning.. I have uncommented the following parameters

LOG_CHECKPOINT_INTERVAL
LOG_CHECKPOINT_TIMEOUT

and set FAST_START_MTTR_TARGET to 60... Still dint see any big difference. Has anyone started using FAST_START_MTTR_TARGET for automatic checkpoint tuning ? Document says if we just need checkpoint tuning, we need to set this higher.. but it doesn't say how higher.. Im thinking of going back to old boat of setting using interval value or FAST_START_MTTR_TARGET to a very high no#. . Any comments please.

Automatic Checkpoint Tuning in 10g: 265831.1 REDO LOGS SIZING ADVISORY: 274264.1
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http://www.freelists.org/webpage/oracle-l Received on Mon Jun 25 2007 - 16:56:14 CDT