| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Andrew Sullivan <andrew(at)libertyrms(dot)info> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: pg_xlog safety |
| Date: | 2003-01-27 23:15:12 |
| Message-ID: | 200301272315.h0RNFCi20958@candle.pha.pa.us |
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| Lists: | pgsql-general |
Andrew Sullivan wrote:
> On Sun, Jan 26, 2003 at 05:26:15PM -0500, Bruce Momjian wrote:
> >
> > If you raid has battery-backed RAM cach in your controller, there is no
> > advantage to putting WAL on a separate disk --- was that the case?
>
> That was always my view, as well. But someone presented me with an
> argument that it would somehow be better to use separate disks inside
> the array in order to make this faster (i.e. it'd still be faster
> because there'd be no contention for spindles). So, I tried it, but
> I could see no difference no matter what I did.
With battery-backed RAM, you would have to fill up that cache faster
than it can flush it (at its leasure) to the disk. It would take a heck
of a lot of activity to cause that.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
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