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RE: Redo Logs - Raid 1 or No Raid

From: Mladen Gogala <mladen_at_wangtrading.com>
Date: Fri, 15 Aug 2003 08:14:29 -0800
Message-ID: <F001.005CAECE.20030815081429@fatcity.com>


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-----

ave
Phillips
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
  INET: mladen_at_wangtrading.com

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