PReviously, I've had a situation where a volume was not created on the backend iscsi but the entry was created in the db on openstack. So when we tried to delete the volume from openstack it would go into "error deleting" status because it could not find the volume on the backend to delete - I am assuming. To workaround this, I deleted the entry from the cinder db like: "mysql>update volumes set deleted=1,status='deleted',deleted_at=now(),updated_at=now() where deleted=0 and id='8022e762-7d9f-435b-ab36-412e903c2756';
Now I have a situation where there are some snapshots that really do exist in the backend but it looks like a recent OS upgrade of the backend iscsi has changed the backend api and now the snapshot deleterequests from openstack are not understood by the backend. I have manually deleted one snapshot on the backend. Openstack still has this listed under volume snapshots.