On Thu, Mar 05, 2015 at 02:19:01PM +0100, Christoph Hellwig wrote:
> On Wed, Mar 04, 2015 at 03:41:41PM +1100, Dave Chinner wrote:
> > As I understand it, nothing will prevent this - if you don't change
> > the UUID on the filesystem when you clone it, then the UUID will
> > still match and writes can be directed to any block deice with a
> > matching offset/UUID pair.
> Unfortunately that's the case indeed. The whole discovery part of
> the block layout protocol is fundamentally flawed, as is the recall
> part. This is my attempt to fix it, but I have no idea how to proceed
> from posting my draft to the IETF to actually making it a standard:
Keep asking, I guess.
I'll try to give it a review too.
May be another reason we can't keep it on by default, if it all it takes
is some confusion with snapshots and something disastrous happens on
upgrade to a block pnfs-supporting kernel.
Though maybe that's really a client bug, as it should probably be
getting an OK from someone before using a device. Arguably the
"systemctl start nfs-blkmap" or equivalent is that, but something more
explicit might be better.