From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750756AbVKXOIx (ORCPT ); Thu, 24 Nov 2005 09:08:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751122AbVKXOIx (ORCPT ); Thu, 24 Nov 2005 09:08:53 -0500 Received: from pne-smtpout1-sn2.hy.skanova.net ([81.228.8.83]:52938 "EHLO pne-smtpout1-sn2.hy.skanova.net") by vger.kernel.org with ESMTP id S1750756AbVKXOIw (ORCPT ); Thu, 24 Nov 2005 09:08:52 -0500 Date: Thu, 24 Nov 2005 15:08:25 +0100 From: Daniel Nilsson To: Bill Davidsen Cc: Markus.Lidel@shadowconnect.com, Linux Kernel Mailing List Subject: Re: Performance degradation when using partitions Message-ID: <20051124140825.GA15298@oden.homeip.net> References: <20051109182300.GA27452@oden.homeip.net> <43833DD9.2060108@tmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <43833DD9.2060108@tmr.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks Daniel