Return-Path: Delivered-To: 2-oracle-l@orafaq.com Received: (qmail 24390 invoked from network); 28 Feb 2008 08:13:54 -0600 Received: from freelists-180.iquest.net (HELO turing.freelists.org) (206.53.239.180) by static-ip-69-64-49-119.inaddr.intergenia.de with SMTP; 28 Feb 2008 08:13:54 -0600 Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 2873B81431E; Thu, 28 Feb 2008 09:13:54 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 03575-01; Thu, 28 Feb 2008 09:13:54 -0500 (EST) Received: from turing (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 8E9BA81471B; Thu, 28 Feb 2008 09:13:53 -0500 (EST) Received: with ECARTIS (v1.0.0; list oracle-l); Thu, 28 Feb 2008 08:38:08 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 33A5981583D for ; Thu, 28 Feb 2008 08:38:08 -0500 (EST) Received: from turing.freelists.org ([127.0.0.1]) by localhost (turing.freelists.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 29850-10 for ; Thu, 28 Feb 2008 08:38:08 -0500 (EST) Received: from outbound.icp-qv1-irony-out3.iinet.net.au (outbound.icp-qv1-irony-out3.iinet.net.au [203.59.1.148]) by turing.freelists.org (Avenir Technologies Mail Multiplex) with ESMTP id 87C3D815834 for ; Thu, 28 Feb 2008 08:38:07 -0500 (EST) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Ao8CAN5Hxkd8qlft/2dsb2JhbAAIiUSkXw X-IronPort-AV: E=Sophos;i="4.25,419,1199631600"; d="scan'208";a="231461320" Received: from unknown (HELO [10.1.1.6]) ([124.170.87.237]) by outbound.icp-qv1-irony-out3.iinet.net.au with ESMTP; 28 Feb 2008 22:38:05 +0900 Message-ID: <47C6B93C.1030307@iinet.net.au> Date: Fri, 29 Feb 2008 00:38:04 +1100 From: Nuno Souto User-Agent: Mozilla Thunderbird 0.6 (Windows/20040502) X-Accept-Language: en-us, en MIME-Version: 1.0 CC: "oracle-l@freelists.org" Subject: Re: DBWR - How Many is Too Many? References: <69eafc3f0802271053y7e60d267j950981c458d93833@mail.gmail.com> In-Reply-To: <69eafc3f0802271053y7e60d267j950981c458d93833@mail.gmail.com> Content-Type: text/plain; charset=us-ascii; format=flowed X-archive-position: 5866 X-ecartis-version: Ecartis v1.0.0 Sender: oracle-l-bounce@freelists.org Errors-to: oracle-l-bounce@freelists.org X-original-sender: dbvision@iinet.net.au Precedence: normal Reply-to: dbvision@iinet.net.au List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: oracle-l X-List-ID: oracle-l List-subscribe: List-owner: List-post: List-archive: X-list: oracle-l X-Virus-Scanned: Debian amavisd-new at localhost.localdomain David Barbour wrote,on my timestamp of 28/02/2008 5:53 AM: > We recently moved our database to a new SAN. Performance has just > tanked. Here's the environment: > AIX5.3L > Oracle 9.2.0.7 > SAN - IBM DS4800 Aye... > sar is scary (just a small portion) > > AIX r3prdci1 3 5 00CE0B8A4C00 02/27/08 > > System configuration: lcpu=8 > > 00:00:00 %usr %sys %wio %idle physc > 02:15:01 19 19 42 19 4.00 > 02:20:00 21 25 40 14 4.00 > 02:25:00 19 18 43 20 4.00 > 02:30:00 18 18 43 21 4.00 > 02:35:00 20 24 40 16 4.00 wio is w-a-a-a-a-a-y too high with sys time low, might well be a I/O misconfiguration. > 1. One db writer for each database disk - in our case that would be 8 > 2. CPUs/8 adjusted for multiples of CPU groups - in our case that would > be 4 > > Any thoughts? Large datablock waits in db, plus lots of wio in the OS. I'm thinking possible misconfiguration of the AIX Disk I/O pacing parameters. From memory, it's: smitty chgsys and check all file systems for minpout and maxpout values. Unless you know in detail the I/O balance of your system, you're much better off with these two set at 0 (zero). There are papers at IBM on this subject, gogle for "IBM AIX disk I/O Pacing". Had a similar situation a while ago: a new SAN's file systems for some reason ended up with 30/30 for both pout pars. When we set them to 0, the wio dropped very significantly. At least worth checking. -- Cheers Nuno Souto in rainy Sydney, Australia dbvision@iinet.net.au -- http://www.freelists.org/webpage/oracle-l