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RE: Redo Logs - Raid 1 or No Raid

From: Mladen Gogala <>
Date: Fri, 15 Aug 2003 08:14:29 -0800
Message-ID: <>

If there is a part of oracle database that you want protected at all times, that part would be redo logs.
I love my redo logs as they can help me to recover the database, if needed. If you go on 4 non-RAID disks,
make sure that each group has at least 2 members. The more groups you have, less you will wait on
archiver. To paraphrase Orwell, 4 groups good, 2 groups bad (George Orwell: Disk Farm). Also, in order
to have better performance, you don't want 3 checkpoints a minute, so do yourself a favor and have
those redo logs files sized decently, around 500M or more. That would give 8x0.5G=4G. That is not
a big amount of space. I'm not sure about Windoze stuff, but the other part of the advice would be to
put them on raw devices to avoid double buffering.    


Mladen Gogala
Oracle DBA

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

Sent: Friday, August 15, 2003 11:49 AM
To: Multiple recipients of list ORACLE-L

Hello all

Oracle 8.1.7
Windoze 2000
Archive Mode - OLTP System

Which do you think is a better set up for the Redo Logs:  2 Groups on 2 Raid1 or 4 Groups on 4 separate non-raid disks? Granted you gain fault tolerance with the mirriored pair, but is that really needed if you multiplex group members over 4 different disks?

As usual we are working with clients that have limited number of disks to work, so 4 Raid1's is not an option ;)

Does anyone have multiple log groups on the same physical drive(s). For example, 4 log groups, 2 members each, with group

1&3 on drive A, and 2&4 on drive B? Does this really gain you anything?

Any ideas and comments are welcome. Thanks for all the help.

David Phillips
Support DBA

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Author: Mladen Gogala

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