DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma;
	h=mime-version:in-reply-to:references:date:message-id:subject:from:to
	:cc:content-type:content-transfer-encoding;
	b=lb8l/rkDryN1k0G68tVfNRgVkVAxe2Y0aCO9Cqg7Z0lCzfN0UgP15hoTEJpVlo5LQ5
	W04CHRiWkqbuu1y3Rb1MpZzbdJuWPpn/a+xTMTbL1ucLiHExD0fs9Ve/b60qtohIR8+S
	Kwal31Okn+Us3aRD4/yzwDa0CoKPtQhBgqQL0=
MIME-Version: 1.0
In-Reply-To: <alpine.DEB.1.10.0903271026590.20251@asgard.lang.hm>
References: <491f66a50903260547p552f6d86kc51f8988898c19e4@mail.gmail.com>
	<alpine.DEB.1.10.0903271026590.20251@asgard.lang.hm>
Date: Fri, 27 Mar 2009 13:33:18 -0700
Message-ID: <72dbd3150903271333pfd63105i8076bf26858eaee1@mail.gmail.com>
Subject: Re: I have a fusion IO drive available for testing
From: David Rees <drees76@gmail.com>
To: david@lang.hm
Cc: Dave Cramer <pg@fastcrypt.com>, pgsql-performance@postgresql.org
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

On Fri, Mar 27, 2009 at 10:30 AM,  <david@lang.hm> wrote:
> On Thu, 26 Mar 2009, Dave Cramer wrote:
>> So far using dd I am seeing around 264MB/s on ext3, 335MB/s on ext2 write
>> speed. So the question becomes what is the best filesystem for this drive?
>
> until the current mess with ext3 and fsync gets resolved, i would say it
> would probably be a bad choice. I consider ext4 too new, so I would say XFS
> or ext2 (depending on if you need the journal or not)

If you're worried about the performance implications of ext3 in
data=ordered mode, the best thing to do is to mount the filesystem in
data=writeback mode instead.

If you're only using the filesystem for PostgreSQL data or logs, your
data will be just as safe except now that data and metadata won't be
forced to disk in the order it was written.

And you still get the benefit of a journal so fsck's after a crash will be fast.

XFS probably is a decent choice, but I don't have much experience with
it except on a desktop system where I can tell you that having write
barriers on absolutely kills performance of anything that does a lot
of filesystem metadata updates.  Again, not a big concern if the
filesystem is only being used for PostgreSQL data or logs.

-Dave