On Jan 19, 2009 20:39 -0600, Dave Kleikamp wrote: > On Tue, 2009-01-20 at 07:36 +0800, Andreas Dilger wrote: > > The whole point of fsid (for NFS) is that this identifies the filesystem > > over reboot, even if the block device ID changes, or if the filesystem > > doesn't have a block device at all (e.g. cluster filesystem). > > I guess that just demonstrates how little I know about what the fsid is > about. Would it be preferable for file systems that have a uuid to use > that instead? Of course anything is an improvement over zeroes. Yes, that is what the ext* patches do - fold the 128-bit UUID into a 64-bit fsid so that it is constant across reboots. The chance of UUID collision is about 1/2^32 due to birthday paradox, which is fairly low, and in case this happens one of the filesystem UUIDs can be regenerated. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
