Re: RAID 1 or 10 for Oracle redo/control files?

From: Tanel Poder <tanel.poder.003_at_mail.ee>
Date: Mon, 2 Feb 2004 20:52:30 +0200
Message-ID: <00b401c3e9bd$b656d2e0$eafb23d5@porgand>

> I've been asked to prove why the Redos shouldn't be RAID 10, because the
> striping should allow for faster writes. I remember reading that this was
> nullified by the sequential nature of the writes, but I can't remember
where
> I saw this.

Well, if you have all the logs on since RAID 10, then the IOs caused by archiving a log will be disturbing LGWR writes (causing lot's of extra head movement for disks). This means occassional performance degradation for both ARCH and LGWR processes.
But if you have spread your odd redos to one disk set and even ones to another set, then the archiver can copy away the logs without disturbing LGWR at all.

This is feasible approach for environments where disk IO on redolog spindles is the bottleneck (btw, your SANs cache may relieve this issue a lot if configured properly).

Tanel.

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Received on Mon Feb 02 2004 - 12:52:30 CST