'Return name of the consistency group for the volume.
cg-name is a volume uniqe identifier (legacy attribute)
and not consistency group as it may imply.'

def _get_volume_cg_name(self, name):

    xml_tree = self.vpsa.send_cmd('list_volumes')
    volume = self._xml_parse_helper(xml_tree, 'volumes', ('display-name', name))
    if (volume is not None):
        return volume.findtext('cg-name')
    return None
