From: Chris Browne <cbbrowne@acm.org>
Subject: Re: XFS filessystem for Datawarehousing
Date: Wed, 02 Aug 2006 18:43:38 -0400
Organization: cbbrowne Computing Inc
Lines: 34
Message-ID: <603bcekbc5.fsf@dba2.int.libertyrms.com>
References: <C0F55F2D.2B856%llonergan@greenplum.com>
	<01cb01c6b676$8ef67330$0a00a8c0@trivadis.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
User-Agent: Gnus/5.1007 (Gnus v5.10.7) XEmacs/21.4.19 (linux)
Cancel-Lock: sha1:gNG+XUn9s7qm4SzrCDs6g0FWoXI=
To: pgsql-performance@postgresql.org

makulev@gmx.net ("Milen Kulev") writes:
> I am pretty exited whether XFS will clearly outpertform ETX3 (no
> default setups for both are planned !).  I am not sure whether is it
> worth to include JFS in comparison too ...

I did some benchmarking about 2 years ago, and found that JFS was a
few percent faster than XFS which was a few percent faster than ext3,
on a "huge amounts of writes" workload.

That the difference was only a few percent made us draw the conclusion
that FS performance was fairly much irrelevant.  It is of *vastly*
more importance whether the filesystem will survive power outages and
the like, and, actually, Linux hasn't fared as well with that as I'd
like. :-(

The differences are small enough that what you should *actually* test
for is NOT PERFORMANCE.

You should instead test for reliability.

- Turn off the power when the DB is under load, and see how well it
  survives.

- Pull the fibrechannel cable, and see if the filesystem (and
  database) survives when under load.

If you find that XFS is 4% faster, that's likely a *terrible*
trade-off if it only survives power outage half as often as (say)
ext3.
-- 
(reverse (concatenate 'string "gro.gultn" "@" "enworbbc"))
http://cbbrowne.com/info/wp.html
"C  combines the power of  assembler language  with the convenience of
assembler language."  -- Unknown