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 0C5B99DCA3E for ; Tue, 24 Jan 2006 13:08:43 -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 47866-02 for ; Tue, 24 Jan 2006 13:08:41 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from hosting.commandprompt.com (128.commandprompt.com [207.173.200.128]) by postgresql.org (Postfix) with ESMTP id E52319DCA18 for ; Tue, 24 Jan 2006 13:08:40 -0400 (AST) Received: from [192.168.1.101] (or-67-76-146-141.sta.sprint-hsd.net [67.76.146.141]) (authenticated bits=0) by hosting.commandprompt.com (8.13.4/8.13.4) with ESMTP id k0OGwoU1003434; Tue, 24 Jan 2006 08:58:54 -0800 Message-ID: <43D65F3E.9040107@commandprompt.com> Date: Tue, 24 Jan 2006 09:09:18 -0800 From: "Joshua D. Drake" User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 To: Brad Nicholson CC: pgsql-performance@postgresql.org Subject: Re: Investigating IO Saturation References: <43D65736.9020905@ca.afilias.info> <43D658D3.5070808@commandprompt.com> <43D65DFC.2040107@ca.afilias.info> In-Reply-To: <43D65DFC.2040107@ca.afilias.info> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeded SMTP AUTH authentication, not delayed by milter-greylist-1.6 (hosting.commandprompt.com [192.168.1.101]); Tue, 24 Jan 2006 08:58:55 -0800 (PST) X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.078 required=5 tests=[AWL=0.078] X-Spam-Score: 0.078 X-Spam-Level: X-Archive-Number: 200601/421 X-Sequence-Number: 16899 Brad Nicholson wrote: > Joshua D. Drake wrote: > >> Brad Nicholson wrote: >> >>> I'm investigating a potential IO issue. We're running 7.4 on AIX >>> 5.1. During periods of high activity (reads, writes, and vacuums), >>> we are seeing iostat reporting 100% disk usage. I have a feeling >>> that the iostat numbers are misleading. I can make iostat usage >>> jump from less than 10% to greater than 95% by running a single >>> vacuum against a moderate sized table (no noticeable change in the >>> other activity). >>> >> Well that isn't surprising. Vacuum is brutal especially on 7.4 as >> that is pre background writer. What type of IO do you have available >> (RAID, SCSI?) >> > Data LUN is RAID 10, wal LUN is RAID 1. How many disks? > >