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 51D6D9DCDA9 for ; Fri, 16 Dec 2005 20:25:26 -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 84261-03 for ; Fri, 16 Dec 2005 20:25:27 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from flake.decibel.org (flake.decibel.org [67.100.216.10]) by postgresql.org (Postfix) with ESMTP id 6ACAC9DCDA8 for ; Fri, 16 Dec 2005 20:25:22 -0400 (AST) Received: by flake.decibel.org (Postfix, from userid 1001) id 051AA15284; Fri, 16 Dec 2005 18:25:25 -0600 (CST) Date: Fri, 16 Dec 2005 18:25:25 -0600 From: "Jim C. Nasby" To: pgsql-performance@postgresql.org Subject: Re: SAN/NAS options Message-ID: <20051217002525.GC53809@pervasive.com> References: <439FC9B8.8020709@paradise.net.nz> <20051216221801.GT53809@pervasive.com> <20051216225103.GE2883@mathom.us> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051216225103.GE2883@mathom.us> X-Operating-System: FreeBSD 4.11-RELEASE-p10 i386 X-Distributed: Join the Effort! http://www.distributed.net User-Agent: Mutt/1.5.9i X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.022 required=5 tests=[AWL=0.022] X-Spam-Score: 0.022 X-Spam-Level: X-Archive-Number: 200512/415 X-Sequence-Number: 16236 On Fri, Dec 16, 2005 at 05:51:03PM -0500, Michael Stone wrote: > On Fri, Dec 16, 2005 at 04:18:01PM -0600, Jim C. Nasby wrote: > >Even if you're doing a lot of random IO? I would think that random IO > >would perform better if you use smaller (8K) blocks, since there's less > >data being read in and then just thrown away that way. > > The overhead of reading an 8k block instead of a 32k block is too small > to measure on modern hardware. The seek is what dominates; leaving the > read head on a little longer and then transmitting a little more over a > 200 megabyte channel is statistical fuzz. True, but now you've got 4x the amount of data in your cache that you probably don't need. Looks like time to do some benchmarking... -- 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