I have a long-running ZFS pool under Ubuntu, which has been through many upgrades. After upgrade from Ubuntu 20 to 22, the encrypted filesystems refuse to mount, though the rest seem OK. zpool status -v reports a permanent error ZFS-8000-8A at the root of the encrypted filesystem. I note that there's a big jump in the package version of zfsutils-linux from 0.8.3 to 2.1.5.
The pool can still be imported to an Ubuntu 20 system, and the encrypted filesystem can still be mounted there. It looks OK. What's more, I'm able to zfs send from Ubuntu 20 and zfs receive on Ubuntu 22, with apparent success.
If I zfs send the entire pool (or do it in parts) from Ubuntu 20 (ZFS 0.8.3) to Ubuntu 22 (ZFS 2.1.5) and the operation succeeds, will I have created a pool free of upgrade problems? That is, will the receive operation build a pool that is fully up-to-date with ZFS? Or could the compatibility problems come across the link?
I do not know enough about the level at which zfs send/receive operates to be sure that I won't have further corruption under Ubuntu 22.
I'm happy to re-encrypt the encrypted filesystems if necessary, rather than sending them raw. Everything would be happening locally. In this case, the Ubuntu 20 is running in an LXD VM with the disk devices attached, and the send/receive pipe is not crossing any network.
Please note that I am aware of the advice to scrap the entire pool and restore it from backup. I'm attempting to recover without having to resort to that, since I appear to be able to read the pool.
All disks pass long SMART tests, and scrubbing the pool under Ubuntu 20 shows no errors.
I'd be very pleased to be told (with citations) that the error is confined to the encrypted filesystems and that I can replace them and proceed without rebuilding the whole pool, but I don't know enough about ZFS internals to be sure of that. I would be interested in how to find out.