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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