X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 775959DC826 for ; Fri, 10 Feb 2006 18:38:39 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 23014-08 for ; Fri, 10 Feb 2006 18:38:41 -0400 (AST) X-Greylist: delayed 00:06:41.766064 by SQLgrey- Received: from mx1.hive.is (isaserver.ipf.is [85.197.192.10]) by postgresql.org (Postfix) with SMTP id C6D6B9DC800 for ; Fri, 10 Feb 2006 18:38:33 -0400 (AST) Received: (qmail 16656 invoked by uid 0); 10 Feb 2006 22:31:58 +0000 Received: from unknown (HELO ?192.168.1.34?) (85.197.216.186) by postur.hive.is with SMTP; 10 Feb 2006 22:31:58 +0000 Subject: Re: Large Database Design Help From: Ragnar To: pgsql-performance@postgresql.org In-Reply-To: <43EC69EA.3010709@logix-tt.com> References: <43EB92DA.2080607@orangekids.org> <43EC69EA.3010709@logix-tt.com> Content-Type: text/plain Date: Fri, 10 Feb 2006 22:39:54 +0000 Message-Id: <1139611194.17929.105.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.1.1 Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.268 required=5 tests=[AWL=0.268] X-Spam-Score: 0.268 X-Spam-Level: X-Archive-Number: 200602/118 X-Sequence-Number: 17104 On Fri, 2006-02-10 at 11:24 +0100, Markus Schaber wrote: > For lots non-read-only database workloads, RAID5 is a performance > killer. Raid 1/0 might be better, or having two mirrors of two disks > each, the first mirror holding system, swap, and the PostgreSQL WAL > files, the second one holding the data. I was under the impression that it is preferable to keep the WAL on its own spindles with no other activity there, to take full advantage of the sequential nature of the WAL writes. That would mean one mirror for the WAL, and one for the rest. This, of course, may sometimes be too much wasted disk space, as the WAL typically will not use a whole disk, so you might partition this mirror into a small ext2 filesystem for WAL, and use the rest for files seldom accessed, such as backups. gnari