RE: Multiplex Redo Logs with Mirrored Disks?

From: Stephen Evans <evans036_at_mc.duke.edu>
Date: Tue, 23 Nov 2004 15:11:33 -0500
Message-ID: <OFADC52818.3EFFF21A-ON85256F55.006E8036-85256F55.006EEC82@notes.duke.edu>

i have experienced multi disk failures within a single raid group. it always seems to happen after the array has been powered off (i guess the spindles seize or something).
so, yes multiplex your redos & cf's

we actually tri-plex redos & controlfiles. one copy goes on local unix storage & the other two go on the SAN. That way even if the SAN catches on fire (or whatever), we can still get to our active redos & control files.

good luck,

steve

"Nick Tilbury @ Northampton" <ntilbury
Sent by: oracle-l-bounce_at_freelists.org
11/23/2004 11:48 AM
Please respond to ntilbury  

        To: "'dwagoner_at_arsenaldigital.com'" <dwagoner_at_arsenaldigital.com>, "ORACLE-L (E-mail)" <oracle-l_at_freelists.org>

        cc: 
        Subject:        RE: Multiplex Redo Logs with Mirrored Disks?

IMHO - What you are questionning is 'best-practice' and relying on hardware
solutions to get
you out of any potential failures. I'd say your on a slippery slope. Stick with best practice and have at least 2 members per group.

Nick
-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of David Wagoner Sent: 23 November 2004 15:47
To: ORACLE-L (E-mail)
Subject: Multiplex Redo Logs with Mirrored Disks?

Is there any need to multiplex redo logs with mirrored disks (e.g., RAID-1 or RAID-1+0)?
Example- Oracle recommends multiplexing redo logs on separate disks, like redo01a.log on Disk1 and redo01b.log on Disk2, etc.

However, now that mirrored disks are in common use with RAID-1+0, RAID-1, etc. it seems that sufficient protection is in place to use only a single copy of each redo log. This would also provide the benefit of reduced disk
I/O to write redo information to disk.

Anyone disagree?

Best regards,

David B. Wagoner
Database Administrator

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http://www.freelists.org/webpage/oracle-l Received on Tue Nov 23 2004 - 17:04:12 CST