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Re: RAID card recommendation

From: Jochen Erwied <jochen(at)pgsql-performance(dot)erwied(dot)eu>
To: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: RAID card recommendation
Date: 2009-11-24 20:59:04
Message-ID: 1704708990.20091124215904@erwied.eu (view raw or flat)
Thread:
Lists: pgsql-performance
Tuesday, November 24, 2009, 9:05:28 PM you wrote:

> Have you searched the -performance archives for references to them?
> I'm not that familiar with Adaptec RAID controllers.  Not requiring a
> battery check / replacement is nice.

Either I searched for the wrong terms, or there isn't really that much
reference on RAID-controllers on this list. Aberdeen is menthioned once and
looks interesting, but I didn't find a reseller in Germany. As far as I see
from the list, Promise and Adaptec both seem to be not too bad choices.

> So, you're willing (or forced by economics) to suffer downtime due to
> drive failure every so often.

I haven't experienced any downtime due to a disk failure for quite a while 
now (call me lucky), although I had a really catastrophic experience with a 
RAID-5 some time ago (1 drive crashed, the second one during rebuild :-()

But for this application losing one day of updates is not a big deal, and 
downtime isn't either. It's a long running project of mine, with growing 
storage needs, but not with 100% of integrity or uptime.

> So, assuming this means an 8 hour work day for ~20M rows, you're
> looking at around 700 per second.

It's an automated application running 24/7, so I require 'only' about 
200-250 updates per second.

> I'd definitely test the heck out of whatever RAID card you're buying
> to make sure it performs well enough.  For some loads and against some
> HW RAID cards, SW RAID might be the winner.

Well, I haven't got so much opportunities to test out different kind of 
hardware, so I have to rely on experience or reports.

> Another option might be a JBOD box attached to the machine that holds
> 12 or so 2.5" 15k like the hitachi ultrastar 147G 2.5" drives.  This
> sounds like a problem you need to be able to throw a lot of drives at
> at one time.  Is it likely to grow much after this?

JBOD in an external casing would be an alternative, especially when using 
an external case. And no, the database will not grow too much after 
reaching its final size.

But looking at the prices for anything larger than 4+1 drives in an
external casing is not funny at all :-(

-- 
Jochen Erwied     |   home: jochen(at)erwied(dot)eu     +49-208-38800-18, FAX: -19
Sauerbruchstr. 17 |   work: joe(at)mbs-software(dot)de  +49-2151-7294-24, FAX: -50
D-45470 Muelheim  | mobile: jochen(dot)erwied(at)vodafone(dot)de       +49-173-5404164


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