From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o43Bo5h4151871 for ; Mon, 3 May 2010 06:50:05 -0500 Received: from mail.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 69EC81DE3387 for ; Mon, 3 May 2010 04:52:10 -0700 (PDT) Received: from mail.internode.on.net (bld-mail15.adl6.internode.on.net [150.101.137.100]) by cuda.sgi.com with ESMTP id BDbJ2ZjC64XKKSHK for ; Mon, 03 May 2010 04:52:10 -0700 (PDT) Date: Mon, 3 May 2010 21:52:07 +1000 From: Dave Chinner Subject: Re: read slower than write on "mv"? Message-ID: <20100503115207.GE2591@dastard> References: <201005031054.38817@zmi.at> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <201005031054.38817@zmi.at> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Michael Monnerie Cc: xfs@oss.sgi.com On Mon, May 03, 2010 at 10:54:28AM +0200, Michael Monnerie wrote: > This is not XFS specific, I see it on every filesys. I do a > "mv . /newlocation" and see this with iostat: > > Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq- > sz avgqu-sz await svctm %util > xvdb 608,60 2,60 25967,20 102,40 85,31 5,37 > 8,77 1,58 96,72 > xvdg 0,00 608,60 0,00 26532,10 87,19 7,55 > 12,41 0,12 7,44 > > Reading takes 97% I/O time, writing 7%. This is on the same raidset, but > I see the same when copying between two different single disks also. Or > is it just an effect of write caching that writes look faster than > reads? Yes, just an effect of write caching hiding IO latency. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs