I've followed this blog about applying QOS to cinder volumes backed by Ceph: http://ceph.com/planet/openstack-ceph...

The QOS policy gets applied to any new volumes created using this new volume-type. Existing volumes can be 'retyped' to the new type, only if they are not in-use:

ERROR: Invalid input received: Retype cannot change front-end qos specs for in-use volume

Additionally, since I have some volumes created using the volume-type before the QOS policy was attached, those volumes do not get the QOS policy until after they are rebuilt.

How can I apply a retrospective QOS policy to all existing volumes with ZDT (0 down time) for those volumes?