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 432129DC880 for ; Fri, 16 Dec 2005 20:48:00 -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 84588-09 for ; Fri, 16 Dec 2005 20:48:03 -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 374CC9DC883 for ; Fri, 16 Dec 2005 20:47:57 -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 <0IRM0029OA81DSI2@vms042.mailsrvcs.net> for pgsql-performance@postgresql.org; Fri, 16 Dec 2005 18:48:01 -0600 (CST) Received: from localhost (localhost [127.0.0.1]) by osgiliath.mathom.us (Postfix) with ESMTP id B82B1600662 for ; Fri, 16 Dec 2005 19:48:00 -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 30829-06 for ; Fri, 16 Dec 2005 19:48:00 -0500 (EST) Received: by osgiliath.mathom.us (Postfix, from userid 1000) id 82525600442; Fri, 16 Dec 2005 19:48:00 -0500 (EST) Date: Fri, 16 Dec 2005 19:48:00 -0500 From: Michael Stone Subject: Re: SAN/NAS options In-reply-to: <20051217002525.GC53809@pervasive.com> To: pgsql-performance@postgresql.org Mail-followup-to: pgsql-performance@postgresql.org Message-id: <20051217004800.GF2883@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> <20051216225103.GE2883@mathom.us> <20051217002525.GC53809@pervasive.com> User-Agent: Mutt/1.5.11 X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.02 required=5 tests=[AWL=0.020] X-Spam-Score: 0.02 X-Spam-Level: X-Archive-Number: 200512/416 X-Sequence-Number: 16237 On Fri, Dec 16, 2005 at 06:25:25PM -0600, Jim C. Nasby wrote: >True, but now you've got 4x the amount of data in your cache that you >probably don't need. Or you might be 4x more likely to have data cached that's needed later. If you're hitting disk either way, that's probably more likely than the extra IO pushing something critical out--if *all* the important stuff were cached you wouldn't be doing the seeks in the first place. This will obviously be heavily dependent on the amount of ram you've got and your workload, so (as always) you'll have to benchmark it to get past the hand-waving stage. Mike Stone