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 A659D9DC883 for ; Fri, 16 Dec 2005 18:51:06 -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 65693-06 for ; Fri, 16 Dec 2005 18:51:08 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from vms042pub.verizon.net (vms042pub.verizon.net [206.46.252.42]) by postgresql.org (Postfix) with ESMTP id 5443E9DC84E for ; Fri, 16 Dec 2005 18:51:04 -0400 (AST) Received: from osgiliath.mathom.us ([70.108.72.158]) by vms042.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 (built Sep 9 2005)) with ESMTPA id <0IRM002RV4T4DG02@vms042.mailsrvcs.net> for pgsql-performance@postgresql.org; Fri, 16 Dec 2005 16:51:04 -0600 (CST) Received: from localhost (localhost [127.0.0.1]) by osgiliath.mathom.us (Postfix) with ESMTP id 98BD7600662 for ; Fri, 16 Dec 2005 17:51:03 -0500 (EST) Received: from osgiliath.mathom.us ([127.0.0.1]) by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 29765-03-10 for ; Fri, 16 Dec 2005 17:51:03 -0500 (EST) Received: by osgiliath.mathom.us (Postfix, from userid 1000) id 7FA8F600483; Fri, 16 Dec 2005 17:51:03 -0500 (EST) Date: Fri, 16 Dec 2005 17:51:03 -0500 From: Michael Stone Subject: Re: SAN/NAS options In-reply-to: <20051216221801.GT53809@pervasive.com> To: pgsql-performance@postgresql.org Mail-followup-to: pgsql-performance@postgresql.org Message-id: <20051216225103.GE2883@mathom.us> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii; format=flowed Content-disposition: inline X-Pgp-Fingerprint: 53 FF 38 00 E7 DD 0A 9C 84 52 84 C5 EE DF 7C 88 X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at mathom.us References: <439FC9B8.8020709@paradise.net.nz> <20051216221801.GT53809@pervasive.com> User-Agent: Mutt/1.5.11 X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0 required=5 tests=[none] X-Spam-Score: 0 X-Spam-Level: X-Archive-Number: 200512/414 X-Sequence-Number: 16235 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. Mike Stone