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Message-ID: <70c01d1d0808050757j34886207xbcbb76d475319b65@mail.gmail.com>
Date: Tue, 5 Aug 2008 07:57:58 -0700
From: "Mark Wong" <markwkm@gmail.com>
To: david@lang.hm
Subject: Re: file system and raid performance
Cc: pgsql-performance@postgresql.org, "Gabrielle Roth" <gorthx@gmail.com>
In-Reply-To: <alpine.DEB.1.10.0808042201010.22058@asgard.lang.hm>
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References: <70c01d1d0808042154u7b78d988vac1e461a93b0ba10@mail.gmail.com>
	<alpine.DEB.1.10.0808042201010.22058@asgard.lang.hm>

On Mon, Aug 4, 2008 at 10:04 PM,  <david@lang.hm> wrote:
> On Mon, 4 Aug 2008, Mark Wong wrote:
>
>> Hi all,
>>
>> We've thrown together some results from simple i/o tests on Linux
>> comparing various file systems, hardware and software raid with a
>> little bit of volume management:
>>
>> http://wiki.postgresql.org/wiki/HP_ProLiant_DL380_G5_Tuning_Guide
>>
>> What I'd like to ask of the folks on the list is how relevant is this
>> information in helping make decisions such as "What file system should
>> I use?"  "What performance can I expect from this RAID configuration?"
>> I know these kind of tests won't help answer questions like "Which
>> file system is most reliable?" but we would like to be as helpful as
>> we can.
>>
>> Any suggestions/comments/criticisms for what would be more relevant or
>> interesting also appreciated.  We've started with Linux but we'd also
>> like to hit some other OS's.  I'm assuming FreeBSD would be the other
>> popular choice for the DL-380 that we're using.
>>
>> I hope this is helpful.
>
> it's definantly timely for me (we were having a spirited 'discussion' on
> this topic at work today ;-)
>
> what happened with XFS?

Not exactly sure, I didn't attempt to debug much.  I only looked into
it enough to see that the fio processes were waiting for something.
In one case I left the test go for 24 hours too see if it would stop.
Note that I specified to fio not to run longer than an hour.

> you show it as not completing half the tests in the single-disk table and
> it's completly missing from the other ones.
>
> what OS/kernel were you running?

This is a Gentoo system, running the 2.6.25-gentoo-r6 kernel.

> if it was linux, which software raid did you try (md or dm) did you use lvm
> or raw partitions?

We tried mdraid, not device-mapper.  So far we have only used raw
partitions (whole devices without partitions.)

Regards,
Mark