'Pick up migration target pool.'

def _select_migrate_poolnumber(self, volume, pools, xml, option):

    (tmpPools, lds, ldsets, used_ldns, hostports, max_ld_count) = self.configs(xml)
    ldname = self.get_ldname(volume.id, self._properties['ld_name_format'])
    ld = lds[ldname]
    temp_conf_properties = self.get_conf_properties(option)
    size = (volume.size * units.Gi)
    pools = [pool for (pn, pool) in pools.items() if ((pool['free'] >= size) and ((len(temp_conf_properties['pool_pools']) == 0) or (pn in temp_conf_properties['pool_pools'])))]
    selected_pool = self._return_poolnumber(pools)
    if (selected_pool == ld['pool_num']):
        selected_pool = (-1)
    return selected_pool
