The storage system includes a first storage system and a second storage system. The first storage system, which is coupled to a computer and the second storage system, includes a first storage control device and a plurality of first storage units. The second storage system includes a plurality of second storage units. The first storage control device provides the computer with a logical unit assigned to at least one of the second storage units, receives a first access request from the computer and sends a second access request to one of plurality of the second storage units, obtains performance information relating to the second access request, and moves data stored in at least one of the plurality of second storage units to at least one of the first storage units according to the performance information.