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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Way to much log switching!!!
Mark
Do you mean that you are filling logs every 1-2 minutes every hour of the day and night, or is this some type of peak that occurs for a few minutes each day? Some sites operate their ODS in noarchivelogmode. Have you considered that? Have you investigated how long it would take to apply all these logs in the event of a recovery?
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
I said it "looked" clear - Riddick
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Mark Moynahan
Sent: Wednesday, June 30, 2004 2:24 PM
To: oracle-l_at_freelists.org
Subject: Way to much log switching!!!
9.2.0.4
Solaris 5.8
Is it unheard of to have redo logs sized at 500M, 750M or even 1G? Reading the oracle documentation on redo log sizes it mentions that redo logs in the gigabyte size is not abnormal. Does anyone have redo logs larger than 1G? If so, have you had any issues with DBWR and checkpoint behavior?
Currently, we have an ODS system with 3 redo log files sized at 200M each. Looking at v$log_history, the logs are switching every 1 to 2 minutes. If a 200M log switches at 2 minutes then a 400M log should switch in 4 minutes and 1G log should switch in 10 minutes. I've recommended to size the redo to 1G along with determining what is causing all the redo with Logminer. Is 20 minutes a good rule of thumb to go by when seeing how often the redo logs switch?
The Oracle documentation reads:
It is not possible to provide a specific size recommendation for redo log files, but redo log files in the range of a hundred megabytes to a few gigabytes are considered reasonable. Size your online redo log files according to the amount of redo your system generates. A rough guide is to switch logs at most once every twenty minutes. Part Number A96533-02
Thanks,
Mark Moynahan
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