James Allsopp wrote: > On Thu, 26 Nov 2020 at 12:32, Dan Ritter <d...@randomstring.org> wrote: > > > > - cp -a /var to /tank/var > > > - Set the mount point on /tank/var to /var > > > - Remove /var entry from /etc/fstab > > > - Export the pool > > > - Reboot > > > > > > > > > And then I should have a ZFS var for VMs and Docker containers when the > > > main OS imports ZFS for /var. > > > > Don't export the pool. Unmount all ZFS mounts before or as part > > of shutdown.. > > Ok, got all this to work almost; When the system comes back up, it sees no > /var directory and tries to fill it. Then the zfs-mount service starts > later and can't mount over a non-empty directory. I'm out of ideas now.
So you need ZFS to be up earlier. I've never seen anyone use ZFS for /var without also using it for /, but the procedure should be basically the same: you need to get everything set up in your initramfs as though you were going to use a ZFS root, and then don't. See https://openzfs.github.io/openzfs-docs/Getting%20Started/Debian/Debian%20Buster%20Root%20on%20ZFS.html and zfs-initramfs -dsr-
