X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id 4594C52AE9 for ; Sat, 20 Aug 2005 09:15:08 -0300 (ADT) Received: from svr1.postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 77442-02 for ; Sat, 20 Aug 2005 12:15:05 +0000 (GMT) Received: from vms048pub.verizon.net (vms048pub.verizon.net [206.46.252.48]) by svr1.postgresql.org (Postfix) with ESMTP id 9A53052A38 for ; Sat, 20 Aug 2005 09:15:02 -0300 (ADT) Received: from osgiliath.mathom.us ([70.108.53.154]) by vms048.mailsrvcs.net (Sun Java System Messaging Server 6.2 HotFix 0.04 (built Dec 24 2004)) with ESMTPA id <0ILI00F9BSP59W47@vms048.mailsrvcs.net> for pgsql-performance@postgresql.org; Sat, 20 Aug 2005 07:15:06 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by osgiliath.mathom.us (Postfix) with ESMTP id 1C09E6050CD; Sat, 20 Aug 2005 08:15:05 -0400 (EDT) Received: from osgiliath.mathom.us ([127.0.0.1]) by localhost (osgiliath [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 27694-04; Sat, 20 Aug 2005 08:15:04 -0400 (EDT) Received: by osgiliath.mathom.us (Postfix, from userid 1000) id DCD24600498; Sat, 20 Aug 2005 08:15:04 -0400 (EDT) Date: Sat, 20 Aug 2005 08:15:04 -0400 From: Michael Stone Subject: Re: Query plan looks OK, but slow I/O - settings advice? In-reply-to: To: Dan Harris Cc: pgsql-performance@postgresql.org Mail-Followup-To: Dan Harris , pgsql-performance@postgresql.org Message-id: <20050820121504.GL19080@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: <1124434535.3257.7.camel@noodles> User-Agent: Mutt/1.5.9i X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=0.005 required=5 tests=[AWL=0.005] X-Spam-Level: X-Archive-Number: 200508/289 X-Sequence-Number: 14036 On Sat, Aug 20, 2005 at 12:52:08AM -0600, Dan Harris wrote: >On Aug 19, 2005, at 12:55 AM, Jeffrey W. Baker wrote: >> Have you considered booting your >>machine with elevator=deadline? > >Although I'm not the OP for this problem, I thought I'd try it out. >WOW.. this should be in a Pg tuning guide somewhere. [snip] >16-drive RAID 10 Yeah, the default scheduler tries to optimize disk access patterns for a single-spindle setup, and actually makes things worse if you have a device with multiple spindles. Mike Stone