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 7B4E19DCA23 for ; Tue, 24 Jan 2006 13:03:59 -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 43833-10 for ; Tue, 24 Jan 2006 13:03:58 -0400 (AST) X-Greylist: delayed 00:28:53.921475 by SQLgrey- Received: from mail.libertyrms.com (vgateway.libertyrms.info [207.219.45.62]) by postgresql.org (Postfix) with ESMTP id 4899A9DCA0F for ; Tue, 24 Jan 2006 13:03:56 -0400 (AST) Received: from dba5.int.libertyrms.com ([10.1.3.44]) by mail.libertyrms.com with esmtp (Exim 4.22) id 1F1RaG-0008Bj-EA; Tue, 24 Jan 2006 12:03:56 -0500 Message-ID: <43D65DFC.2040107@ca.afilias.info> Date: Tue, 24 Jan 2006 12:03:56 -0500 From: Brad Nicholson User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Joshua D. Drake" CC: pgsql-performance@postgresql.org Subject: Re: Investigating IO Saturation References: <43D65736.9020905@ca.afilias.info> <43D658D3.5070808@commandprompt.com> In-Reply-To: <43D658D3.5070808@commandprompt.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Mail-From: bnichols@ca.afilias.info X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.641 required=5 tests=[AWL=-0.172, INFO_TLD=0.813] X-Spam-Score: 0.641 X-Spam-Level: X-Archive-Number: 200601/419 X-Sequence-Number: 16897 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. -- Brad Nicholson 416-673-4106 bnichols@ca.afilias.info Database Administrator, Afilias Canada Corp.