'Manage an existing volume on the backend storage.'

def manage_existing(self, volume, existing_ref):

    existing_volume_name = self._get_existing_volume_ref_name(existing_ref)
    try:
        cmd = ['volume', 'rename', existing_volume_name, volume['name']]
        self._eql_execute(*cmd)
        self._set_volume_description(volume, '"OpenStack    Managed"')
        self.add_multihost_access(volume)
        data = self._get_volume_info(volume['name'])
        updates = self._get_model_update(data['iSCSI_Name'])
        LOG.info('Backend    volume    %(back_vol)s    renamed    to    %(vol)s    and    is    now    managed    by    cinder.', {'back_vol': existing_volume_name, 'vol': volume['name']})
        return updates
    except Exception:
        with excutils.save_and_reraise_exception():
            LOG.error('Failed    to    manage    volume    "%s".', volume['name'])
