From: Greg Smith <greg@2ndquadrant.com>
To: Grzegorz Jaśkiewicz <gryzman@gmail.com>
Cc: postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: serveRAID M5014 SAS
Date: Wed, 25 May 2011 10:00:49 -0400
Message-ID: <4DDD0B91.9080300@2ndquadrant.com> (raw)
In-Reply-To: <BANLkTi=fE2YCS0Lra42ei1hFrKqXdVk2jA@mail.gmail.com>
References: <BANLkTi=fE2YCS0Lra42ei1hFrKqXdVk2jA@mail.gmail.com>
Grzegorz Jaśkiewicz wrote:
> Does anyone here have any bad experiences with the RAID card in subject ?
> This is in an IBM server, with 2.5" 10k drives.
>
> But we seem to observe its poor performance in other configurations as
> well (with different drives, different settings) in comparison with -
> say, what dell provides.
>
Older ServeRAID cards have never been reported as very fast. They were
an OK controller if you just want to mirror a pair of drives or
something simple like that. Their performance on larger RAID arrays is
terrible compared to the LSI products that Dell uses.
However, the M5014 *is* an LSI derived product, with a proper
battery-backed write cache and everything. I'm not sure if older views
are even useful now. Few things to check:
-Is the battery working, and the write cache set in write-back mode?
-Has read-ahead been set usefully?
-Did you try to use a more complicated RAID mode than this card can handle?
Those are the three easiest ways to trash performance here.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
"PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books
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To: pgsql-performance@postgresql.org
Cc: greg@2ndquadrant.com, gryzman@gmail.com
Subject: Re: serveRAID M5014 SAS
In-Reply-To: <4DDD0B91.9080300@2ndquadrant.com>
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