Am Dienstag, 29. Januar 2013 schrieb Daniel Phillips:
> On Mon, Jan 28, 2013 at 5:40 PM, Theodore Ts'o <tytso@xxxxxxx> wrote:
> > On Mon, Jan 28, 2013 at 04:20:11PM -0800, Darrick J. Wong wrote:
> >> On Mon, Jan 28, 2013 at 03:27:38PM -0800, David Lang wrote:
> >> > The situation I'm thinking of is when dealing with VMs, you make a
> >> > filesystem image once and clone it multiple times. Won't that end up
> >> > with the same UUID in the superblock?
> >> Yes, but one ought to be able to change the UUID a la tune2fs
> >> -U. Even still... so long as the VM images have a different UUID
> >> than the fs that they live on, it ought to be fine.
> > ... and this is something most system administrators should be
> > familiar with. For example, it's one of those things that Norton
> > Ghost when makes file system image copes (the equivalent of "tune2fs
> > -U random /dev/XXX")
> Hmm, maybe I missed something but it does not seem like a good idea
> to use the volume UID itself to generate unique-per-volume metadata
> hashes, if users expect to be able to change it. All the metadata hashes
> would need to be changed.
I believe that is what BTRFS is doing.
And yes, AFAIK there is no easy way to change the UUID of a BTRFS filesystems
after it was created.