Thanks for the input on the *bump* policy of this forum, I was not sure.
As for the zpool command from the zfs-fuse package, I have tried unsuccessfully to mount the device (/dev/sda) using
Opening my eyes a little bit more (RTFM), I tried using only the import option for destroyed pools, and so (to my astonishment) I got:
famille@CXTO:~$ sudo zpool import -d /dev/sda Data
cannot open '/dev/sda/': Not a directory
cannot import 'Data': no such pool available
Ooook. Now I think I am getting somewhere... I plugged my FreeNAS's USB key on my laptop just to access the shell, and asked it what zpool version it was running. It seems that FreeNAS is running on ZFS pool version 28.
famille@CXTO:~$ sudo zpool import -D -f
state: UNAVAIL (DESTROYED)
status: The pool is formatted using an incompatible version.
action: The pool cannot be imported. Access the pool on a system running newer
software, or recreate the pool from backup.
Data UNAVAIL newer version
I double-checked on my Ubuntu box to see what version of ZFS it was running, and it seems that "only" version 23 is installed.
I'll google how to install the 28th version of ZFS on the Ubuntu box and keep updating this thread. If you have any insight, comments or jokes relevant to the topic feel free to comment and provide some input.