From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763522AbXGFKSv (ORCPT ); Fri, 6 Jul 2007 06:18:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755300AbXGFKSm (ORCPT ); Fri, 6 Jul 2007 06:18:42 -0400 Received: from web32603.mail.mud.yahoo.com ([68.142.207.230]:34802 "HELO web32603.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1759403AbXGFKSl (ORCPT ); Fri, 6 Jul 2007 06:18:41 -0400 X-YMail-OSG: zXsOFHQVM1m0gFqP1cT0Rm0N5RaOspOfWRY0eLUiR1AlIwnYlcOCaRz.BOHlN0LQw7OvGgZM1jZza2RAez4sRfHZNg-- X-RocketYMMF: knobi.rm Date: Fri, 6 Jul 2007 03:18:40 -0700 (PDT) From: Martin Knoblauch Reply-To: spamtrap@knobisoft.de Subject: Re: Understanding I/O behaviour To: linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Message-ID: <773157.44861.qm@web32603.mail.mud.yahoo.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> b) any ideas how to optimize the settings of the /proc/sys/vm/ >> parameters? The documentation is a bit thin here. >> >> >I cant offer any advice there, but is raid-5 really the best choice >for your needs? I would not choose raid-5 for a system that is >regularly performing lots of large writes at the same time, dont >forget that each write can require several reads to recalculate the >partity. > >Does the raid card have much cache ram? > 192 MB, split 50/50 to read write. >If you can afford to loose some space raid-10 would probably perform >better. RAID5 most likely is not the best solution and I would not use it if the described use-case was happening all the time. It happens a few times a day and then things go down when all memory is filled with page-cache. And the same also happens when copying large amountd of data from one NFS mounted FS to another NFS mounted FS. No disk involved there. Memory fills with page-cache until it reaches a ceeling and then for some time responsiveness is really really bad. I am just now playing with the dirty_* stuff. Maybe it helps. Cheers Martin ------------------------------------------------------ Martin Knoblauch email: k n o b i AT knobisoft DOT de www: http://www.knobisoft.de