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 7A7059DC816 for ; Fri, 6 Jan 2006 12:37:34 -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 46536-08 for ; Fri, 6 Jan 2006 12:37:33 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from flake.decibel.org (unknown [67.100.216.10]) by postgresql.org (Postfix) with ESMTP id 5ABE09DC84A for ; Fri, 6 Jan 2006 12:37:32 -0400 (AST) Received: by flake.decibel.org (Postfix, from userid 1001) id 252173982E; Fri, 6 Jan 2006 10:37:32 -0600 (CST) Date: Fri, 6 Jan 2006 10:37:32 -0600 From: "Jim C. Nasby" To: Ian Westmacott Cc: pgsql-performance@postgresql.org Subject: Re: improving write performance for logging Message-ID: <20060106163732.GL3902@pervasive.com> References: <43BB0C5C.8020207@computer.org> <1136382865.24450.7.camel@spectre.intellivid.com> <7.0.1.0.2.20060104092139.01c37da0@earthlink.net> <1136390438.24450.49.camel@spectre.intellivid.com> <20060106010822.GK43311@pervasive.com> <1136556006.31602.5.camel@spectre.intellivid.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1136556006.31602.5.camel@spectre.intellivid.com> X-Operating-System: FreeBSD 6.0-RELEASE amd64 X-Distributed: Join the Effort! http://www.distributed.net User-Agent: Mutt/1.5.11 X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.079 required=5 tests=[AWL=0.079] X-Spam-Score: 0.079 X-Spam-Level: X-Archive-Number: 200601/40 X-Sequence-Number: 16518 On Fri, Jan 06, 2006 at 09:00:06AM -0500, Ian Westmacott wrote: > On Thu, 2006-01-05 at 19:08 -0600, Jim C. Nasby wrote: > > On Wed, Jan 04, 2006 at 11:00:38AM -0500, Ian Westmacott wrote: > > > The WAL is a 2-spindle (SATA) RAID0 with its own controller (ext3). > > > The tables are on a 10-spindle (SCSI) RAID50 with dual U320 > > > controllers (XFS). This is overkill for writing and querying the data, > > > but we need to constantly ANALYZE and VACUUM in the > > > background without interrupting the inserts (the app is 24x7). The > > > databases are 4TB, so these operations can be lengthy. > > > > How come you're using RAID50 instead of just RAID0? Or was WAL being on > > RAID0 a typo? > > We use RAID50 instead of RAID0 for the tables for some fault-tolerance. > We use RAID0 for the WAL for performance. > > I'm missing the implication of the question... The problem is that if you lose WAL or the data, you've lost everything. So you might as well use raid0 for the data if you're using it for WAL. Or switch WAL to raid1. Actually, a really good controller *might* be able to do a good job of raid5 for WAL. Or just use raid10. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461