Message-ID: <4336CEAA.7070208@commandprompt.com>
Date: Sun, 25 Sep 2005 09:22:02 -0700
From: "Joshua D. Drake" <jd@commandprompt.com>
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To: PFC <lists@boutiquenumerique.com>
Cc: Dave Cramer <pg@fastcrypt.com>,
	Michael Ben-Nes <miki@canaan.co.il>, pgsql-performance@postgresql.org
Subject: Re: Advice on RAID card
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>
>     Even for RAID5 ? it uses a bit more CPU for the parity calculations.

I honestly can't speak to RAID 5. I don't (and won't) use it. RAID 5 is 
a little brutal when under
heavy write load. I use either 1, or 10.

>     An advantage of software raid, is that if the RAID card dies, you 
> have to  buy the same one ; whether I think that you can transfer a 
> bunch of  software RAID5 disks to another machine if the machine 
> they're in dies...

There is a huge advantage to software raid on all kinds of levels. If 
you have the CPU then I suggest
it. However you will never get the performance out of software raid on 
the high level (think 1 gig of cache)
that you would on a software raid setup.

It is a bit of a tradeoff but for most installations software raid is 
more than adequate.

Sincerely,

Joshua D. Drake


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