'Manage an existing non-openstack DotHill volume
existing_ref is a dictionary of the form:
{\'source-name\': <name of the existing DotHill volume>}'

def manage_existing(self, volume, existing_ref):

    target_vol_name = existing_ref['source-name']
    modify_target_vol_name = self._get_vol_name(volume['id'])
    self.client_login()
    try:
        self.client.modify_volume_name(target_vol_name, modify_target_vol_name)
    except exception.DotHillRequestError as ex:
        LOG.exception('Error    manage    existing    volume.')
        raise exception.Invalid(ex)
    finally:
        self.client_logout()
