If backingstore is 'rbd', then you will need to have a valid configuration in <filename>ceph.conf</filename> and a <filename>ceph.client.admin.keyring</filename> defined.
You can specify the following options :
<replaceable>--rbdname RBDNAME</replaceable> will create a blockdevice named RBDNAME rather than the default, which is the container name.
<replaceable>--rbdpool POOL</replaceable> will create the blockdevice in the pool named POOL, rather than the default, which is 'lxc'.