Re: Redo Log File Sizes
From: Jeremiah Wilton <jeremiah_at_ora-600.net>
Date: Wed, 23 Jan 2008 18:21:47 -0800
Message-ID: <4797F63B.608@ora-600.net>
> When we have two or more processing performing updates, deletes and/or
> inserts at the same time our system slows to a crawl.
>
> I was under the impression that Oracle suggests that Redo Log Files be sized
> so they switch only every 20 minutes or so. Is the frequency of the log
> file switching in the excerpt below normal?
Date: Wed, 23 Jan 2008 18:21:47 -0800
Message-ID: <4797F63B.608@ora-600.net>
Dereck L. Dietz wrote:
>
> When we have two or more processing performing updates, deletes and/or
> inserts at the same time our system slows to a crawl.
>
> I was under the impression that Oracle suggests that Redo Log Files be sized
> so they switch only every 20 minutes or so. Is the frequency of the log
> file switching in the excerpt below normal?
The 20 minute rule is not based in any type of science, and can be filed up there with "BCHR must be 99.9 or greater."
Based on your post, there does not seem to be any evidence or reason to believe that the performance problems are caused by logfile size or switch frequency. You need to look at the wait events on the database at the time if the slowdown. If you are on 10g or above, a time-series history of wait data is available in dba_hist_active_sess_history. Any conjecture without looking at the waits is just that.
Regards,
Jeremiah Wilton
ORA-600 Consulting
http://www.ora-600.net
Received on Wed Jan 23 2008 - 20:21:47 CST