[dm-devel] DM_snapshot_cow filesystem (dmsetup create snapshot)

[Alasdair G Kergon]

On Wed, Nov 30, 2011 at 04:48:05PM -0500, Frederick Grose wrote:
> snapshot Invalid  does seem to prevent even read-only access.

Indeed - once it's invalid, that's the end of it.
If we didn't do that, changes to areas of the origin that hadn't already
changed would start to appear in the 'snapshot' and the snapshot would become a
nonsensical hybrid of the two devices containing no information about which
parts of it got corrupted.

Don't allow your snapshots to run out of space!
If you want to see what you can recover, use that code I mentioned earlier.

Alasdair