I see that support for setting ZFS volblocksize has been merged in 4.23, however I can’t find a way to set the value at VM creation time. The zfs.blocksize key doesn’t seem to be an accepted config value:
lxc launch images:ubuntu/focal ubuntu1 --vm -c zfs.blocksize=16K
Creating ubuntu1
Error: Failed instance creation: Failed creating instance record: Unknown configuration key: zfs.blocksize
Any hints?