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@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
