lxc storage set default volume.zfs.blocksize 64KiB
lxc launch images:ubuntu/focal ubuntu1 --vm
Creating ubuntu1
Error: Failed instance creation: Failed creating instance from image: Invalid value for volume "ubuntu1" option "zfs.blocksize": Blocksize can be change only for filesystem type
So I’m not even sure how this feature is supposed to be used atm.
Also while there are no universally optimal volblocksize values, the current default of 8k is is far from a middle compromise.