My ZFS dataset is gone after system upgrade/reboot (ubuntu)

I did recently upgrade my little NAS to ubuntu 14.04 and initially everything worked fine. I'm used to re-import my ZFS pools after restarts and so it was no surprise when the mount point was gone after a restart 2 days ago. But this time i was not able to re-import it and when i started looking closer the whole ZFS dataset disappeared too and i start to run out of ideas what to try (as do the google results i find).

$ zpool list or zpool status no pools available

$ zfs list no datasets available

$ ls /dev/disk/by-id/ ... disks as i have used them in my config ...none missing

Everything was working fine before a reboot 2 days ago, and before that reboot i did run some upgrades including the kernel (standard upgrade via apt). Re-installing/further upgrading or going back to previous versions (selected in grub) all did not help.

It would be really cool to get it back running, especially since i switched to ZFS for its promised reliability. The nice data redundancy does not help me if the whole storage disappears out of nowhere...

Any ideas?

I had the same Problem. Doing

apt-get install ubuntu-zfs zfsutils

and rebooting solved it for me. For some Reasons ubuntu did not update all zfs-packages. You can see if this is the case at the end of apt-get update output (packages held back)