From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Chinner Subject: Re: 3ware 9650 tips Date: Tue, 17 Jul 2007 08:21:24 +1000 Message-ID: <20070716222124.GF31489@sgi.com> References: <4697CA4D.6020304@etelos.com> <20070716024115.GJ12413810@sgi.com> <20070716122225.GB31489@sgi.com> <469B93CA.30801@sandeen.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <469B93CA.30801@sandeen.net> Sender: linux-raid-owner@vger.kernel.org To: Eric Sandeen Cc: David Chinner , Justin Piszcz , Jon Collette , Joshua Baker-LePain , linux-ide-arrays@lists.math.uh.edu, linux-raid@vger.kernel.org, xfs@oss.sgi.com List-Id: linux-raid.ids On Mon, Jul 16, 2007 at 10:50:34AM -0500, Eric Sandeen wrote: > David Chinner wrote: > > On Mon, Jul 16, 2007 at 12:41:15PM +1000, David Chinner wrote: > >> On Fri, Jul 13, 2007 at 03:36:46PM -0400, Justin Piszcz wrote: > ... > >> If you've got any sort of serious disk array, ext3 is not the filesystem > >> to use.... > > > > To show what the difference is, I used blktrace and Chris Mason's > > seekwatcher script on a simple, single threaded dd command on > > a 12 disk dm RAID0 stripe: > > > > # dd if=/dev/zero of=/mnt/scratch/fred bs=1024k count=10k; sync > > > > http://oss.sgi.com/~dgc/writes/ext3_write.png > > http://oss.sgi.com/~dgc/writes/xfs_write.png > > Were those all with default mkfs & mount options? ext3 in writeback > mode might be an interesting comparison too. Defaults. i.e. # mkfs.ext3 /dev/mapper/dm0 # mkfs.xfs /dev/mapper/dm0 The mkfs.xfs picked up sunit/swidth correctly from the dm volume. Last time I checked, writeback made little difference to ext3 throughput; maybe 5-10% at most. I'll run it again later today... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group