$ mysql
mysql> SELECT CEILING(Total_InnoDB_Bytes*1.6/POWER(1024,3)) RIBPS FROM
    -> (SELECT SUM(data_length+index_length) Total_InnoDB_Bytes
    -> FROM information_schema.tables WHERE engine='InnoDB') A;

+-------+
| RIBPS |
+-------+
|     2 |
+-------+
1 row in set, 17 warnings (2 min 5.24 sec)