Oops, forgot to mention that all the disks would be mirrored through the SSA hardware on the AIX servers. As Karl rightly points out, you'd have to be fairly nuts not to mirror the log file! Also, when I mentioned RAID, I was really just trying to emphasise "striping" the locations. I think I'm leaning towards having the log file on one disk (mirrored) which will also be on a separate controller to the other disks. That would leave me the option of striping the work area and other bits and pieces across the 2 remaining disks (also h/w mirrored).

-----Original Message-----
From: info-ingres-bounces@ams.org [mailto:info-ingres-bounces@ams.org] On Behalf Of Karl & Betty Schendel
Sent: 21 October 2004 17:42
To: info-ingres@ams.org
Subject: Re: [Info-Ingres] Disk configuration for log file


At 4:45 PM +0100 10/21/2004, Gibson Jonathan wrote:
>
>We're in the process of adding more storage to our system and I'm trying to come up with a sensible use of the disks.
>I'm putting ckp, dmp & jnl together on a couple of disks*and*spreading the data over 4 more. That leaves me with 3 disks for the application executable, other ingres files, user files (not a great deal to be honest), a few other odds and sods, work area and log file. My concern really is with the last two. Currently they reside on the same disk which is having an impact on large updates as these often have a lot of sorting to do too. Do I just create a 3 disk RAID and splat it over each disk or would I be better have work on 2 and log on 1 or vice a versa. The other alternative is to make the data RAID 5 disks and just have one each for work and log. I'm hedging towards 2 for work and 1 for log though.
>

Running an unmirrored transaction log is excessively machismo when
you have a machine with 9 drives.

I'd suggest two possibilities:
a) mirror the log on 2 of your 3 extra drives, use the third for
"everything else", and put work on the data drives. With 4 of them
(striped, I assume), that should actually work moderately well.

b) mirror the log on 2 of your 3 extra drives. Stripe up the third
with the two that you were going to use for ckp/dmp/jnl, and put work
there (in addition to the ckp related stuff). Put "everything else"
there also, or on the data disks, or some on each.
If there are disk space concerns with plan (b), put ckp and dmp (but
not jnl) on either or both of your log drives.

Karl

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