Received: from localhost (maia-1.hub.org [200.46.204.191]) by postgresql.org (Postfix) with ESMTP id 18E019FB1CC for ; Tue, 9 Jan 2007 08:33:29 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.191]) (amavisd-new, port 10024) with ESMTP id 74797-09 for ; Tue, 9 Jan 2007 08:33:22 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from noel.decibel.org (noel.decibel.org [67.100.216.10]) by postgresql.org (Postfix) with ESMTP id 046829FA4B6 for ; Tue, 9 Jan 2007 08:33:22 -0400 (AST) Received: by noel.decibel.org (Postfix, from userid 1001) id 72CCE5644A; Tue, 9 Jan 2007 06:33:21 -0600 (CST) Received: (hashcash-sendmail, from uid 1001); Tue, 9 Jan 2007 06:33:15 -0600 Date: Tue, 9 Jan 2007 06:33:15 -0600 From: "Jim C. Nasby" To: Jeff Frost Cc: Alvaro Herrera , Ron , Guy Rouillier , PostgreSQL Performance Subject: Re: High update activity, PostgreSQL vs BigDBMS Message-ID: <20070109123312.GL12217@nasby.net> References: <45935A49.6080602@burntmail.com> <20061229220747.GB15429@alvh.no-ip.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: FreeBSD 6.1-RELEASE-p10 amd64 X-Distributed: Join the Effort! http://www.distributed.net User-Agent: Mutt/1.5.13 (2006-08-11) X-Hashcash: 1:20:070109:jeff@frostconsultingllc.com::GF8mNSg/JO6tOeNL:0000000000 0000000000000000000000003S2b X-Hashcash: 1:20:070109:alvherre@commandprompt.com::Bbbo9qhVjvhGRvuq:00000000000 0000000000000000000000000jnu X-Hashcash: 1:20:070109:rjpeace@earthlink.net::c3slmKhLvClZIUUw:0000000000000000 0000000000000000000000004NPW X-Hashcash: 1:20:070109:guyr-ml1@burntmail.com::r093+PBeaBygR39h:000000000000000 00000000000000000000000000+z X-Hashcash: 1:20:070109:pgsql-performance@postgresql.org::Xz8d6omOu01PKNN1:00000 0000000000000000000000000JlF X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200701/103 X-Sequence-Number: 22704 On Thu, Dec 28, 2006 at 02:15:31PM -0800, Jeff Frost wrote: > When benchmarking various options for a new PG server at one of my clients, > I tried ext2 and ext3 (data=writeback) for the WAL and it appeared to be > fastest to have ext2 for the WAL. The winning time was 157m46.713s for > ext2, 159m47.098s for combined ext3 data/xlog and 158m25.822s for ext3 > data=writeback. This was on an 8x150GB Raptor RAID10 on an Areca 1130 w/ > 1GB BBU cache. This config benched out faster than a 6disk RAID10 + 2 disk > RAID1 for those of you who have been wondering if the BBU write back cache > mitigates the need for separate WAL (at least on this workload). Those are > the fastest times for each config, but ext2 WAL was always faster than the > other two options. I didn't test any other filesystems in this go around. Uh, if I'm reading this correctly, you're saying that WAL on a separate ext2 vs. one big ext3 with data=writeback saved ~39 seconds out of ~158.5 minutes, or 0.4%? Is that even above the noise for your measurements? I suspect the phase of the moon might play a bigger role ;P -- Jim Nasby jim@nasby.net EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)