'Removes the specified snapshot from Cinder management.
Does not delete the underlying backend storage object.
We expect a snapshot name in the existing_ref that matches one in
Purity.'

def unmanage_snapshot(self, snapshot):

    self._verify_manage_snap_api_requirements()
    snap_name = self._get_snap_name(snapshot)
    unmanaged_snap_name = (snap_name + UNMANAGED_SUFFIX)
    LOG.info('Renaming    existing    snapshot    %(ref_name)s    to    %(new_name)s', {'ref_name': snap_name, 'new_name': unmanaged_snap_name})
    self._rename_volume_object(snap_name, unmanaged_snap_name)
