Why can't a zvol be a OSD disk?
root@nas:/etc/pve/rob# pveceph createosd /dev/zvol/z/ceph
unable to get device info for 'zd16'
root@nas:/etc/pve/rob# mkfs.xfs /dev/zvol/z/ceph
specified blocksize 4096 is less than device physical sector size 8192
switching to logical sector size 512...