RE: archivelog performance issues
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxx>
- To: "jdanton1@xxxxxxxxx" <jdanton1@xxxxxxxxx>, "jachang@xxxxxxxx" <jachang@xxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 7 Jul 2009 12:31:43 -0400
I agree with Joseph.
Additionally, in my mind, the decision as to whether you run in archivelog mode
should really be about recoverability and uptime needs. Noarchivelog implies
cold backups. You must take a down time to do the backup. Noarchivelog means
you can only recover up to the point in time of the last good cold backup.
With archivelog mode, you can do hot backups and recoverability is to the point
in time of the last committed transaction. There's lots more flexibility that
archivelog mode offer you, as well. Those are just the two most important
points.
Seems to me, you should make the decision as to whether archivelog mode is a
requirement, and then, if needed, make changes to support your required
performance with it enabled.
In my opinion, for *almost all* production databases, archivelog mode is a
foregone conclusion. In my opinion, there are very few production databases
that can really be adequately served with noarchivelog mode.
In conclusion, as Joseph mentioned, for the size of the database you have and
the transaction volume you're talking about, switching archivelog mode on
shouldn't even noticeable at all.
Some things to check before you switch to archive log mode:
- How frequently are you seeing log switches, at peak load time? Size
your online redo so that you get a switch about every 15-30 minutes, at peak.
- If your load variaes greatly from peak to non-peak, you may want to
use archive_lag_target to get more frequent switches during off-peak times.
- Make sure you have at least three redo log groups.
Hope that helps,
-Mark
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Joey D'Antoni
Sent: Tuesday, July 07, 2009 12:09 PM
To: jachang@xxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: Re: archivelog performance issues
How is your storage arranged? In general, with a database of that size, I can't
imagine a significant performance impact from running in archivelog mode,
unless the storage was horribly misconfigured.
Joseph D'Antoni
Synthes USA
________________________________
From: Julio Aguilar-Chang <jachang@xxxxxxxx>
To: Oracle-L Freelists <oracle-l@xxxxxxxxxxxxx>
Sent: Tuesday, July 7, 2009 12:06:33 PM
Subject: archivelog performance issues
Hello:
What are the performance issues I should be aware of if I decide to enable
archivelog mode on an OLTP database? I just inherited this database (about
40GB in size, ~200 users, ~2000 transactions per day), it is not in archivelog
mode, and the manager who owns it (not well versed in Oracle) tells me that the
previous DBA who just left did not enable archiving for database performance
reasons. The Oracle server is an HP DL385, dual core, with 16GB of memory.
Is there a good reason based on performance for not enabling archivelog mode?
--
*****************************************
Julio Aguilar-Chang
Geophysics Group, EES-17
Los Alamos National Laboratory
jachang@xxxxxxxx<mailto:jachang@xxxxxxxx>
(505) 667-1004 - work
(505) 665-3687 - fax
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