A computer includes a management computer connected to a host computer, first and second primary storage systems, first and second secondary storage systems, a primary external storage system connected to the first and second primary storage systems and a secondary external storage system connected to the first and second secondary storage systems. The management computer controls to start copying as processing for storing copied data in the second storage area into a fourth storage area in response to a command for starting processing for storing copied data in the first storage area into a third storage area.