From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932407AbVKXSbR (ORCPT ); Thu, 24 Nov 2005 13:31:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932641AbVKXSbR (ORCPT ); Thu, 24 Nov 2005 13:31:17 -0500 Received: from mail.tmr.com ([64.65.253.246]:56710 "EHLO gaimboi.tmr.com") by vger.kernel.org with ESMTP id S932407AbVKXSbQ (ORCPT ); Thu, 24 Nov 2005 13:31:16 -0500 Message-ID: <43860970.3090804@tmr.com> Date: Thu, 24 Nov 2005 13:41:52 -0500 From: Bill Davidsen Organization: TMR Associates Inc, Schenectady NY User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.11) Gecko/20050729 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Daniel Nilsson CC: Markus.Lidel@shadowconnect.com, Linux Kernel Mailing List Subject: Re: Performance degradation when using partitions References: <20051109182300.GA27452@oden.homeip.net> <43833DD9.2060108@tmr.com> <20051124140825.GA15298@oden.homeip.net> In-Reply-To: <20051124140825.GA15298@oden.homeip.net> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Daniel Nilsson wrote: >On Tue, Nov 22, 2005 at 10:48:41AM -0500, Bill Davidsen wrote: > > >>Daniel Nilsson wrote: >> >> >>>While setting up a software RAID-5 array I started looking into the >>>performance aspect of using partioned drives versus the whole disks >>>for a RAID-5 array. I have an Adaptec 2400a controller which through >>>the I2O kernel driver gives me access to 4x 250GB disks (JBOD mode). >>> >>> >>Did you get an answer on this? And does it happen if you use the drives >>directly, /dev/hdN or /dev/sdN instead of using I2O? I didn't see an >>obvious speed penalty in raw access of drives vs. partitions, but I >>lacked the hardware to really match your setup, particularly the I2O use >>vs. direct access to /dev/sd[ef]. >> >> > >Bill, > >No, I didn't get an answer on this. I've done some more experiments >with the drives, but since they are connected to an Adaptec 2400A RAID >controller (in JBOD mode) I need to go through some I2O driver in or >to see the drives at all. So I never have direct access to these >drives as /dev/hdN or /dev/sdN. There are however two different >drivers available for this RAID controller, one is the standard I2O >driver and the other one is the Adaptec dpt_i2o driver. > >The results are the same though whether I use the Linux I2O driver or >the Adaptec dpt_i2o, the software raid array is rebuilding at roughly >half the speed when the drives are partioned. I don't know what other >data to provide in ordet to get any further in the testing. > > Unfortunately, until someone else has the time and interest to make more tests I don't see a good next step. I might be able to at least do some better quantified tests later this weekend, but I have no I2O devices, so it isn't going to tell much. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979