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Re: Perc 3 DC

From: Glyn Astill <glynastill(at)yahoo(dot)co(dot)uk>
To: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Perc 3 DC
Date: 2008-11-22 16:59:02
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
--- On Sat, 22/11/08, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> You really have two choices.  First is to try and use it as
> a plain
> SCSI card, maybe with caching turned on, and do the raid in
> software.
> Second is to cut it into pieces and make jewelry out of it.

Haha, I'm not really into jewelry, although I had thought of smacking it into a pile of dust with a lump hammer, that's much more my thing.

>  Anything
> before the Perc 6 series is seriously brain damaged, and
> the Perc6
> brings the dell raid array line squarly in line with a 5
> year old LSI
> megaraid, give or take.  And that's being generous.

Well this card thinks it's a 5 year old lsi megaraid. I've got a pile of perc5i megaraid paperweights on my desk at work, so this was kinda expected really.

> > I've tried writeback and write through modes,
> tried changing cache flush times, disabled and enabled
> multiple PCI delayed transactions, all seem to have little
> effect.
> Yeah, it's like trying to performance tune a yugo.

Did I mention I drive a yugo?

> > Finally I decided to wave goodbye to Dell's
> firmware. LSI has it down as a MegaRAID 493 elite 1600, so I
> flashed it with their latest firmware.  Doesn't seem to
> have helped either though.
> Does it have a battery backup module?  Often you can't
> really turn on
> write-back without one.  That would certainly slow things
> down.  But
> you should certainly expect > 20 M/s on a modern RAID
> controller
> writing out to a 4 disk RAID10

Yeah the battery's on it, that and the 128Mb is really the only reason I thought I'd give it a whirl.


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