Re: Integrated perc 5/i

From: "Merlin Moncure" <mmoncure(at)gmail(dot)com>
To: "Michael Ben-Nes" <miki(at)epoch(dot)co(dot)il>
Cc: "PostgreSQL Performance" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Integrated perc 5/i
Date: 2007-08-16 12:59:51
Message-ID: b42b73150708160559h18502bb9ved421ec4b7be7c1a@mail.gmail.com
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On 8/16/07, Michael Ben-Nes <miki(at)epoch(dot)co(dot)il> wrote:
> Hi
>
> I wanted to know if the integrated perc 5/i which come with Dell 2950 will
> yield maximum performance from RAID 10 ( 15K SAS ).
> Or should I ask for different card ?
>
> I read an old post that shows that RAID 10 does not work eficently under
> perc 5/i
> http://groups.google.com/group/pgsql.performance/browse_thread/thread/b85926fe6de1f6c2/38837995887b6033?lnk=st&q=perc+5%2Fi+performance&rnum=6&hl=en#38837995887b6033
>
> Does any one have any experience with RAID 10 & perc 5/i ?

no, I've tested raid 10 on a few different perc 5/i and never had
those results. raid 10 often gives poor sequential read performance
relative to a raid 5 but better random performance generally, which is
usually more important. That said, the perc 5/e (never done raid 5 on
the 5/i) has posted some of the best raid 5 numbers I've ever seen in
terms of random performance on sata.

merlin

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