From: Greg Smith <gsmith@gregsmith.com>
To: pgsql-performance@postgresql.org
Subject: Re: Experience with HP Smart Array P400 and SATA drives?
Date: Fri, 5 Dec 2008 19:29:49 -0500 (EST)
Message-ID: <Pine.GSO.4.64.0812051900030.27034@westnet.com> (raw)
In-Reply-To: <200812051530.01258@hal.medialogik.com>
References: <4934FE60.30702@sime.com>
<49395B57.EE98.0025.0@wicourts.gov>
<200812051530.01258@hal.medialogik.com>
On Fri, 5 Dec 2008, Alan Hodgson wrote:
> 1) /sbin/blockdev --setra 2048 device (where device is the partition or
> LVM volume)
Normally, when I see write speed dramatically faster than write, it does
mean that something about the read-ahead is set wrong. While I don't have
one to check, it looks to me like the P400 does its own read-ahead though,
which may be more effective to tweak than what Linux does. I'd suggest
taking a look at the settings with HP's admin utility and see how it's set
for that and for allocation of RAM to the read cache. I've seen some
RAID5 configs that put too much caching on the write side by default to
compensate for the deficiencies of that RAID level, and you have to push
some of that back toward the read side to balance it out right.
> 2) Use XFS, and make sure your stripe settings match the RAID.
XFS has good performance, but I can't get over how many system failure
corruption reports I hear about it. In any case, there's no reason this
system shouldn't perform fine on ext3.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com
Subject: Re: Experience with HP Smart Array P400 and SATA drives?
In-Reply-To: <Pine.GSO.4.64.0812051900030.27034@westnet.com>
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