Also I don't think 'cinder-backend' is a valid backend name:
openstack volume type set B --property volume_backend_name=cinder-backup
cinder-backup is a discrete set of functionality within cinder, not an additional backend.
Also I don't think 'cinder-backend' is a valid backend name:
openstack volume type set B --property volume_ backend_ name=cinder- backup
cinder-backup is a discrete set of functionality within cinder, not an additional backend.