Subject: Re: XFS vs Ext3, and schedulers, for WAL
From: "Joshua D. Drake" <jd@commandprompt.com>
Reply-To: jd@commandprompt.com
To: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <4CB34E50.3080201@agliodbs.com>
References: <4CAD0214.50304@agliodbs.com>  <4CB34E50.3080201@agliodbs.com>
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Organization: Command Prompt, Inc.
Date: Mon, 11 Oct 2010 11:06:23 -0700
Message-ID: <1286820383.25541.45.camel@jd-desktop>
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On Mon, 2010-10-11 at 10:50 -0700, Josh Berkus wrote:
> > There's a number of blog tests floating around comparing XFS and Ext3,
> > and the various Linux schedulers, for PGDATA or for an all-in-one mount.
> > 
> > However, the WAL has a rather particular write pattern, and it's
> > reasonable to assume that it shouldn't be optimized the same way as
> > PGDATA.  Has anyone done any head-to-heads for WAL drive configuration
> > changes?
> 
> That would be a "no", then.  Looks like I have my work cut out for me ...

The only thing I have done is:

http://www.commandprompt.com/blogs/joshua_drake/2008/04/is_that_performance_i_smell_ext2_vs_ext3_on_50_spindles_testing_for_postgresql/

It doesn't cover XFS but it provides a decent and simple comparison on
ext2/ext3 etc...

Remember xlog is sequential so pushing it off is useful.

JD

> 
> -- 
>                                   -- Josh Berkus
>                                      PostgreSQL Experts Inc.
>                                      http://www.pgexperts.com
> 

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