A storage network system that can be kept running despite a failure in a host computer is provided. A computer system includes: first, second and third storage systems which store data and are connected to one another; a primary host computer connected to the first storage system; a secondary host computer connected to the second storage system; and a management portion which manages data transfer between the storage systems, in which the management portion sets the storage systems such that, while the primary host computer is in operation, data stored in the first storage system is transferred to the second storage system and data stored in the second storage system is transferred to the third storage system, and wherein the management portion sets the storage systems such that, while the secondary host computer is in operation, data stored in the second storage system is transferred to the first storage system and data stored in the first storage system is transferred to the third storage system.