On Thu, Mar 27, 2008 at 03:26:55PM -0400, christopher barry wrote: > On Wed, 2008-03-26 at 13:58 -0700, Lombard, David N wrote: > ... > > > Can you point me at any docs that describe how best to implement snaps > > > against a gfs lun? > > > > FYI, the NetApp "snapshot" capability is a result of their "WAFL" filesystem > > <http://www.google.com/search?q=netapp+wafl>. Basically, they use a > > copy-on-write mechanism that naturally maintains older versions of disk blocks. > > > > A fun feature is that the multiple snapshots of a file have the identical > > inode value > > > > fun as in 'May you live to see interesting times' kinda fun? Or really > fun? The former. POSIX says that two files with the identical st_dev and st_ino must be the *identical* file, e.g., hard links. On a snapshot, they could be two *versions* of a file with completely different contents. Google suggests that this contradiction also exists elsewhere, such as with the virtual FS provided by ClearCase's VOB. -- David N. Lombard, Intel, Irvine, CA I do not speak for Intel Corporation; all comments are strictly my own. -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
