Hacker News Reader

Comment by kop316 | Hacker News Reader

I used zfs on Linux with encrypted / for a while on Debian. It works really well, but unfortunately when I upgraded from Jessie to Buster, it did not recognize how I set it up and broke the system. I ended up having to reinstall.

View on HN

BTW, did you do a traditional in-place upgrade via apt? I've once or twice managed to break boot between Debian releases.. But not since lilo/early grub days.

Sounds like you probably ran into zfs not being in Debian proper - and buster unlocking dmcrypt, but not being able to mount zfs? Should normally be salvageable via booting previous Jessie kernel and initial ram/root disk (initrd).

At any rate, I gather you've moved on - just sound like an unlucky break - even with root on unsupported zfs.

Yeah I did an in-place upgrade via apt. I for some reason thought zfs was in debian proper (contrib vs. main). Like I said in another post, I may try doing that again.

But then again, the main reason I haven't is because all of my stuff is backed up via Nextcloud, so reinstalling Debian is pretty quick/painless for me.

Related: I moved to a new laptop at work with a zfs send over ssh of /home/myuser - and a mount+manual copy of what I wanted. Very straight forward - but not that different from an rsync to /home/myuser/olfstuff.

Zfs encryption was still a bit new, so both boxes uses dmcrypt on full disk plus efi plus /boot (technically redundant, but it works).

Looking forward to hopefully root on encrypted zfs in next Ubuntu lts.

Did you take a snapshot before performing the upgrade, and did you try to restore the previous snapshot before the reinstall?

Curious if snapshots can protect you even as far as OS upgrades gone wrong. I'd assume they can, if all filesystems are ZFS + snapshotted.

I've used (conceptually equivalent) btrfs snapshots to let me install arch and gentoo, always easily rolling back to my own heavily customized Ubuntu system. I've never tried it, but given a copy of the snapshot tools, you should even be able to rollback from formatting your root partition.

I think there are even some tools to do this directly in GRUB, at least for btrfs. We can have automatically created list of available snapshots.

To be honest I didn't feel like tinkering with it, I just reinstalled. Right now it is on ext4.

My issue was that for some reason Linux no longer could find the encrypted partition to decrypt, so I couldn't get it up to a point where I could even work with it.

Ah that's a shame. If you'd had a bootable USB stick or some pre-boot environment to use, you probably could have rolled back from a snapshot. At least, that's my understanding of the theory.

Your experience has definitely not discouraged me from wanting to ZFS my root partitions though. If only to provide the potential / theoretical ability to roll back a snapshot if necessary!

To be honest, it was laziness on my part, I could have probably figured it out and fixed it. The snapshot ability was incredibly nice, don't get me wrong. I really liked it on my system. I may switch back in the near future.

I can post my "script" when I get home if you want to try it. I use script very liberally, it was my notes of the commands I used in order in order to get ZFS/dmcrypt working.

Hm, you used zfsonlinux 0.8 under Jessie? Or was this prior to general release of native encryption support?

What do you mean by "native" encryption? I used dmcrypt+LUKS. That is file system agonistic.

That's not zfs encryption, that's "just" encryption (ed: with zfs on top).

(open) Zfs now has native encryption:

https://github.com/zfsonlinux/zfs/releases/tag/zfs-0.8.0

(ed: there are some potential benefits to zfs encryption - it's as cross platform as zfs (encrypt an USB drive, use on Linux, os x, windows, freebsd).

Zfs send/receive - receiver can take your encrypted backup - key doesn't have to travel.

Mount drives across dual boot - share encrypted /home between dual boot windows and Linux?

Not sure - but I think volume encryption is supported too. Might simplify encrypted swap (if you already "pay" for zfs). Note: there are apparently some issues with swap on zfs (volumes at least, possibly files too)

If you don't need suspend/resume - suppose you could share one encrypted swap volume across multiboot environments..) )

Heh, ok neat! I did not use that then.

If you did on Jessie I'd be more than a little impressed! :)

zfs import -af?

Like I said elsewhere, I could have probably fixed it, but I was lazy. I also wanted to try out Wayland, but I ended up going back to Xfce. Maybe when Xfce moves to Wayland I will try again.

Reply on news.ycombinator.com