From: Greg Smith <greg@2ndQuadrant.com>
To: pgsql-performance@postgresql.org
Subject: Re: Raid 5 vs Raid 10 Benchmarks Using bonnie++
Date: Wed, 17 Aug 2011 17:17:31 -0400
Message-ID: <4E4C2FEB.5060301@2ndQuadrant.com> (raw)
In-Reply-To: <75A85649-2B95-43D5-8404-4776D2E580EC@darkstatic.com>
References: <959BD2FA-0312-458B-BD5F-ED358D2C47ED@darkstatic.com>
<f4e06a7cad34ee9217a3e57fd4eb0e67.squirrel@sq.gransy.com>
<D89151D3-D2E5-47E3-8B90-4A573DAB5FFA@darkstatic.com>
<75A85649-2B95-43D5-8404-4776D2E580EC@darkstatic.com>
On 08/17/2011 02:26 PM, Ogden wrote:
> I am using bonnie++ to benchmark our current Postgres system (on RAID
> 5) with the new one we have, which I have configured with RAID 10. The
> drives are the same (SAS 15K). I tried the new system with ext3 and
> then XFS but the results seem really outrageous as compared to the
> current system, or am I reading things wrong?
>
> The benchmark results are here:
> http://malekkoheavyindustry.com/benchmark.html
Congratulations--you're now qualified to be a member of the "RAID5
sucks" club. You can find other members at
http://www.miracleas.com/BAARF/BAARF2.html Reasonable read speeds and
just terrible write ones are expected if that's on your old hardware.
Your new results are what I would expect from the hardware you've
described.
The only thing that looks weird are your ext4 "Sequential Output -
Block" results. They should be between the ext3 and the XFS results,
not far lower than either. Normally this only comes from using a bad
set of mount options. With a battery-backed write cache, you'd want to
use "nobarrier" for example; if you didn't do that, that can crush
output rates.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
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To: pgsql-performance@postgresql.org
Cc: greg@2ndQuadrant.com
Subject: Re: Raid 5 vs Raid 10 Benchmarks Using bonnie++
In-Reply-To: <4E4C2FEB.5060301@2ndQuadrant.com>
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