From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p6MNFpMS113477 for ; Fri, 22 Jul 2011 18:15:51 -0500 Received: from ipmail06.adl2.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id D94028134F for ; Fri, 22 Jul 2011 16:10:49 -0700 (PDT) Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id jZlWm7ot5Fc0Rvnv for ; Fri, 22 Jul 2011 16:10:49 -0700 (PDT) Date: Sat, 23 Jul 2011 09:10:40 +1000 From: Dave Chinner Subject: Re: 30 TB RAID6 + XFS slow write performance Message-ID: <20110722231040.GD13963@dastard> References: <4E24907F.6020903@johnbokma.com> <201107210820.01019@zmi.at> <20110721064838.GA13963@dastard> <201107220810.01889@zmi.at> <4E29BBDA.3000603@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4E29BBDA.3000603@hardwarefreak.com> 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: Stan Hoeppner Cc: Michael Monnerie , John Bokma , xfs@oss.sgi.com On Fri, Jul 22, 2011 at 01:05:14PM -0500, Stan Hoeppner wrote: > On 7/22/2011 1:10 AM, Michael Monnerie wrote: > > > Yes, I just wanted to know about the corner cases, and how XFS behaves. > > Actually, we're changing over to using NetApps, and with their WAFL > > anyway I should drop all su/sw usage and just use 4KB blocks. > > I've never used a NetApp filer myself. However, that said, I would > assume that WAFL is only in play for NFS/CIFS transactions since WAFL is > itself a filesystem. Netapp's website is busted, so here's a cached link: http://webcache.googleusercontent.com/search?q=cache:9DdO2a16hdIJ:blogs.netapp.com/extensible_netapp/2008/10/what-is-wafl--3.html+netapp+san+wafl&cd=1&hl=en&ct=clnk&source=www.google.com "The point is that WAFL is the part of the code that provides the 'read or write from-disk' mechanisms to both NFS and CIFS and SAN. The semantics of a how the blocks are accessed are provided by higher level code not by WAFL, which means WAFL is not a file system." If you can be bothered trolling for that entire series of blog posts in the google cache, it's probably a good idea so you can get a basic understanding of what WAFL actually is. > When exposing LUNs from the same filer to FC and iSCSI hosts I would > assume the filer acts just as any other SAN controller would. It has it's own quirks, just like any other FC attached RAID array... > In this case I would think you'd probably still want to align your > XFS filesystem to the underlying RAID stripe from which the LUN > was carved. Which actually matters very little when WAFL between the FS and the disk because WAFL uses copy-on-write and stages all it's writes through NVRAM and so you've got no idea what the alignment of any given address in the filesystem maps to, anyway. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs