'create volume_name on ETERNUS from id on OpenStack.'

def _create_volume_name(self, id_code):

    LOG.debug('_create_volume_name,    id_code:    %s.', id_code)
    if (id_code is None):
        msg = _('_create_volume_name,    id_code    is    None.')
        LOG.error(msg)
        raise exception.VolumeBackendAPIException(data=msg)
    m = hashlib.md5()
    m.update(id_code.encode('utf-8'))
    volumename = base64.urlsafe_b64encode(m.digest()).decode()
    ret = (VOL_PREFIX + six.text_type(volumename))
    LOG.debug('_create_volume_name,    ret:    %s', ret)
    return ret
