I'm interested in teh ZFS snapshot feature, So I deployed 20.04 VM with ZFS. I created a snapshot to test how the rollback procedure works.
sudo snapshot -r rpool@SNAP1
When then I created and deleted a few test files.
I rebooted to grub went to histroy, selected my snapshot.
Booted into Ubuntu, and nothing has changed, the files I deleted are still deleted and the files I copied after the snapshot are still copied. My understanding is rolling back to a snapshot would bring the filesystem to the state at the time the snapshot was created.
So I did some more testing, added and deleted some files, created a new snapshot
sudo snapshot -r rpool@SNAP2
rebooted to Grub menu, went to history, now, I do not see my latest snapshot, the first one is still there, but not the new one.
So I went in Ubuntu and destroyed the first snapshot and rebooted to grub, just to find the first snapshot is still listed in the grub history menu..
Am I missing something ?