apt-clone fails to create snapshot

[unifiednick]

When trying to run an upgrade apt-clone fails to create the snapshot.

apt-clone.SystemCallError: Unable to create snapshot 'syspool/rootfs-nmu-002@nmu-003': cannot create snapshot 'syspool/rootfs-nmu-002@nmu-003': dataset does not exist

zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT
syspool/backup/dump@05-02-2009 0 - 52.2G -
syspool/data/media@05-02-2009 83K - 355G -
syspool/rootfs-nmu-000@initial 64.2M - 751M -
syspool/rootfs-nmu-000@nmu-001 3.68M - 829M -
syspool/rootfs-nmu-001@nmu-002 12.5M - 834M -
syspool/rootfs-nmu-002@nmu-003 6.42M - 834M -

[Tim Spriggs (tim-tajinc)]

I've seen similar errors while setting snapshots but they are intermittent in the latest build

[Tim Spriggs (tim-tajinc)]

nexenta.org is reliably reproducing the snapshot bug now.

root@nexenta:~# zfs snapshot tank/ncp2/hardy-unstable@test
root@nexenta:~# zfs destroy tank/ncp2/hardy-unstable@test
root@nexenta:~# zfs list -H -o name -tall -r tank/ncp2/hardy-unstable
tank/ncp2/hardy-unstable
tank/ncp2/hardy-unstable@hardy-testing
tank/ncp2/hardy-unstable@previous
tank/ncp2/hardy-unstable@latest
root@nexenta:~# zfs destroy tank/ncp2/hardy-unstable@previous
cannot destroy 'tank/ncp2/hardy-unstable@previous': dataset does not exist

Running the destroy command repeatedly gives the same error. Attempting to look in the snapshot directory yields:

root@nexenta:/tank/ncp2/dists/hardy-unstable/.zfs/snapshot# ls -la
total 3
dr-xr-xr-x 4 root root 4 Dec 30 18:58 .
dr-xr-xr-x 3 root root 3 Dec 30 18:58 ..
drwxr-xr-x 8 root sys 12 Jan 1 15:13 hardy-testing
drwxr-xr-x 9 root sys 13 Feb 9 21:12 latest
?--------- ? ? ? ? ? previous

Finally, renaming the snapshot seems to work but removing the renamed snapshot still provides no effect:

root@nexenta:~# zfs rename tank/ncp2/hardy-unstable@previous tank/ncp2/hardy-unstable@previous-
root@nexenta:~# zfs destroy tank/ncp2/hardy-unstable@previous-
cannot destroy 'tank/ncp2/hardy-unstable@previous-': dataset does not exist

root@nexenta:~# zfs list tank/ncp2/hardy-unstable@previous-
NAME USED AVAIL REFER MOUNTPOINT
tank/ncp2/hardy-unstable@previous- 54.3M - 33.3G -

the fact that "zfs rename" works may provide a work-around for some applications (like apt-clone) if the user is careful. The cause of the problem is still not known.