Received: from localhost (unknown [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 38B8E6504AB for ; Sun, 6 Jul 2008 12:18:30 -0300 (ADT) Received: from postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 86409-07 for ; Sun, 6 Jul 2008 12:18:27 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from westnet.com (westnet.com [216.187.52.2]) by postgresql.org (Postfix) with ESMTP id C1CDA6504AA for ; Sun, 6 Jul 2008 12:18:26 -0300 (ADT) Received: from westnet.com (localhost [127.0.0.1]) by westnet.com (8.14.0/8.14.0) with ESMTP id m66FIP7o017745; Sun, 6 Jul 2008 11:18:25 -0400 (EDT) Received: from localhost (gsmith@localhost) by westnet.com (8.14.0/8.13.2/Submit) with ESMTP id m66FIOFx017741; Sun, 6 Jul 2008 11:18:25 -0400 (EDT) X-Authentication-Warning: westnet.com: gsmith owned process doing -bs Date: Sun, 6 Jul 2008 11:18:24 -0400 (EDT) From: Greg Smith X-X-Sender: gsmith@westnet.com To: Jaime Casanova cc: psql performance list Subject: Re: filesystem options for WAL In-Reply-To: <3073cc9b0807052204j14efa56ft113b50013cacddcf@mail.gmail.com> Message-ID: References: <3073cc9b0807052204j14efa56ft113b50013cacddcf@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200807/56 X-Sequence-Number: 30656 On Sun, 6 Jul 2008, Jaime Casanova wrote: > Here http://www.westnet.com/~gsmith/content/postgresql/TuningPGWAL.htm I read: > """ > Combining these two, an optimal fstab for the WAL might look like this: > > /dev/hda2 /var ext3 defaults,writeback,noatime 1 2 > """ > Is this info accurate? Nah, that guy doesn't know what he's talking about. That article is overdue for an overhaul. > I also read on other document from the "technical documentation" that > for partitions where you have the tables and indexes is better to have > journaling and for partitions for the WAL is better to not have > journalling... The WAL is itself a sort of journal, and the way writes to it are done the filesystem level journaling that ext3 provides doesn't buy you much beyond additional overhead. Check out http://www.commandprompt.com/blogs/joshua_drake/2008/04/is_that_performance_i_smell_ext2_vs_ext3_on_50_spindles_testing_for_postgresql/ for an extensive comparison of different options here, where you can see that using ext2 instead can be much more efficient. The main downside of ext2 is that you might get longer boot times from running fsck, but it won't be any less reliable for database use though. -- * Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD