From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id oBN0sat7059916 for ; Wed, 22 Dec 2010 18:54:36 -0600 Received: from mail.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 7385114786DA for ; Wed, 22 Dec 2010 16:56:33 -0800 (PST) Received: from mail.internode.on.net (bld-mail16.adl2.internode.on.net [150.101.137.101]) by cuda.sgi.com with ESMTP id iB6kPX4sjxpANmeK for ; Wed, 22 Dec 2010 16:56:33 -0800 (PST) Date: Thu, 23 Dec 2010 11:56:30 +1100 From: Dave Chinner Subject: Re: Anyone using XFS in production on > 20TiB volumes? Message-ID: <20101223005630.GJ4907@dastard> References: <20101222175611.1c7d5190@harpe.intellique.com> <4D124B71.9030401@sandeen.net> <20101223012655.2681c596@galadriel.home> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Justin Piszcz Cc: Eric Sandeen , xfs@oss.sgi.com On Wed, Dec 22, 2010 at 07:28:29PM -0500, Justin Piszcz wrote: > = > = > On Thu, 23 Dec 2010, Emmanuel Florac wrote: > = > >Le Wed, 22 Dec 2010 13:03:13 -0600 vous =E9criviez: > > > >>http://xfs.org/index.php/XFS_FAQ#Q:_I_want_to_tune_my_XFS_filesystems_f= or_.3Csomething.3E > >> > >>which mentions getting your geometry right if it's hardware raid > >>that can't be detected automatically. > > > >Just as a side note : I tried several times to manually set the > >filesystem layout to precisely match the underlying hardware RAID > >with sunit and swidth but didn't find that it made a noticeable > >difference. On my 39.9 TB systems, the default agcount is 39, while the > >optimum would be (theorically at least) 42. > = > Hi, I concur, for hardware raid (at least on 3ware cards) I have > found it makes no difference, thanks for confirming. I'd constrain that statement to "no difference for the workloads and hardware tested". Indeed, testing an empty filesystem will often show no difference in performance, because typically problems don't show up until you've started to age the filesystem significantly. When the filesystem has started to age, the difference between having done lots of stripe unit/width aligned allocation vs none can be very significant.... Hence don't assume that because you can't see any difference on a brand new, empty filesystem there never will be a difference over the life of the filesytem... Cheers, Dave. -- = Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs