From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id BB0C67CA0 for ; Mon, 18 Jul 2016 05:10:51 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay2.corp.sgi.com (Postfix) with ESMTP id 7BEAB304043 for ; Mon, 18 Jul 2016 03:10:48 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id nV4dFWSdzLZ4jUy6 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Mon, 18 Jul 2016 03:10:47 -0700 (PDT) Date: Mon, 18 Jul 2016 12:10:41 +0200 From: Carlos Maiolino Subject: Re: mkfs.xfs -d su=XXX,sw=YYY and future volume resize Message-ID: <20160718101041.GA3788@redhat.com> References: <20160715094647.GD3608@redhat.com> <20160715230725.GV1922@dastard> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20160715230725.GV1922@dastard> 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 Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: Marcin Sura , xfs@oss.sgi.com On Sat, Jul 16, 2016 at 09:07:25AM +1000, Dave Chinner wrote: > On Fri, Jul 15, 2016 at 11:46:47AM +0200, Carlos Maiolino wrote: > > On Thu, Jul 14, 2016 at 10:19:02PM +0200, Marcin Sura wrote: > > > Hi, > > > When I create filesystem I can specify su and sw paramteres which match > > > underlying storage device. > > > So for example, If I have raid 6 volume made of 6 + 2 disks with stripe > > > size of 256k I create xfs with: > > > mkfs.xfs -d su=256k,sw=6 > > > But what if I will extend original volume by 2 disks. sw will 8. Will > > > be there a performance panelty compared to filesystem created from > > > scratch with correct sw parameter? > > > BR > > > Marcin > > > > Complementing Dave's answer, you can also mount the filesystem with new > > alignment configuration. > > > > You can use: sunit=value and swidth=value for mounting the FS with the new > > settings. man xfs for more info. > > That doesn't change the fact that everything that already existed in > the filesystem would now be misaligned and hence have performance > issues on read and/or overwrite. Only newly written data will be > aligned to the new stripe width. > > Also, keep in mind that stripw width cahnges are an alignment change > you generally canot make through the mount options. Static metadata > such as allocation group headers are laid out according to the > physical geometry of the filesystem, and that cannot be changed. > hence the mount options can only change the stripe unit/width when > they don't change the alignment constraints. e.g. doubling of the > stripe width will work because the alignemtn of the stripe units is > still the same. However, changing from 6 disks to 8 won't work > because it is a different physical alignment... > Thanks for the detailed info, it was my bad to have not predicted such details > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com > > _______________________________________________ > xfs mailing list > xfs@oss.sgi.com > http://oss.sgi.com/mailman/listinfo/xfs -- Carlos _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs