Yeah the lxd snap bundles several versions of the zfs user land including 2.2 so if the host kernel provides the right zfs module version it will use it.
I may be being a bit dense here, but although my server has Linux 6.x on it with VFS idmap support, it only has ZFS 2.1.5, which doesn’t supposedly support idmapping? Yet, it is working (or at least it seems to be). I’m not sure what I’m missing!?
Your kernel has a newer version of ZFS than the userland tooling.
But because LXD bundles its own userland tooling in the snap, it can benefit from your newer kernel without you needing update the tooling on your system.
Your kernel has a newer version of ZFS than the userland tooling.
But because LXD bundles its own userland tooling in the snap, it can benefit from your newer kernel without you needing update the tooling on your system.
Ah, okay, the penny has dropped. I didn’t realise (or didn’t understand) that the feature doesn’t require the on-disk structures to be updated, and had forgotten that zfs ships with the kernel rather than as a separate module in a different package. So basically, I have ZFS 2.2.x in the kernel, userland ZFS 2.1.5 tools (zfsutils-linx), and LXD ships with multiple ZFS versions, so it picks the one that works with the kernel version. And hence it works. Thank you for spoon-feeding me! I think I now understand.