X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (unknown [200.46.204.144]) by svr1.postgresql.org (Postfix) with ESMTP id B2F09528B2 for ; Mon, 30 May 2005 02:18:31 -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 16881-01 for ; Mon, 30 May 2005 05:18:30 +0000 (GMT) Received: from hummer.onthenet.com.au (hummer.OntheNet.com.au [203.13.68.9]) by svr1.postgresql.org (Postfix) with ESMTP id 0CCB75287A for ; Mon, 30 May 2005 02:18:29 -0300 (ADT) Received: from [192.168.2.24] (imp5.dsl.onthenet.net [203.144.16.135]) by hummer.onthenet.com.au (Postfix) with ESMTP id 495F519FBD1 for ; Mon, 30 May 2005 15:18:27 +1000 (EST) Message-ID: <429B90D1.9030402@wildcash.com> Date: Mon, 30 May 2005 15:16:49 -0700 From: Rudi Starcevic User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040616 X-Accept-Language: en-us, en MIME-Version: 1.0 To: POSTGRES-PERFORMANCE Subject: Re: slow queries, possibly disk io References: <4a0cafe205052613242e0d4d10@mail.gmail.com> <758d5e7f05052614232f6c9164@mail.gmail.com> <4a0cafe205052706043ef8f53f@mail.gmail.com> <4a0cafe205052706042d4e60e5@mail.gmail.com> <14584.1117204158@sss.pgh.pa.us> In-Reply-To: <14584.1117204158@sss.pgh.pa.us> X-Enigmail-Version: 0.86.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, hits=2.329 tagged_above=0 required=5 tests=DATE_IN_FUTURE_12_24 X-Spam-Level: ** X-Archive-Number: 200505/428 X-Sequence-Number: 12592 Hi, I had some disk io issues recently with NFS, I found the command 'iostat -x 5' to be a great help when using Linux. For example here is the output when I do a 10GB file transfer onto hdc Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util hdc 0.00 875.95 0.00 29.66 0.00 7244.89 0.00 3622.44 244.27 3.07 103.52 1.78 5.27 The last field show the disk is 5.27% busy. I have seen this value at 100%, adding more server brought it under 100%. It seems that if you hit 100% problems sort of cascade all over that place. For example Apache connections went right up and hit their max. I am not sure how accurate the % is but it has work pretty well for me. Perhaps use this command in another window with you run your SQL and see what it shows. HTH. Kind regards, Rudi.