Hi,all When we configured backend_host (not host) for cinder-volume HA, then we execute the cli "cinder-manage db online_data_migrations", and we can get the following error: "Error attempting to run shared_targets_online_data_migration: MessagingTimeout: Timed out waiting for a reply to message ID".The problem can be reproduced by deploying cinder-volume with pacemaker.And I have set the backend_host = hostgroup, the "host" is not set. The reason of this I found that there will be an rpc call for all service.host. When the service.host is "hostgroup@ssd", because the "hostgroup" host is virtual, so theis is error. I have raise this as a bug. Can you tell me more about this? Thank you very much. Ref: https://github.com/openstack/cinder/blob/master/cinder/cmd/manage.py#L111 https://bugs.launchpad.net/cinder/+bug/1824509 Best Regards Rambo