To eliminate delay of data update processing in a primary volume in a remote copy system.

It is assumed that at least one of a synchronous copy system for updating data of the primary volume 24 after confirming that the data are copied to a secondary volume 44 and an asynchronous copy system for updating the data of the primary volume 24 before confirming that the data are copied to the secondary volume 44 is adopted. The data of the primary volume 24 are updated by an instruction from a higher order host 21, and a response time required for copying the data to the secondary volume 44 is monitored when copying the updated data to the secondary volume 44. At that time, when adopting the synchronous copy system and the monitored response time becomes a prescribed time or above, the asynchronous copy system is adopted instead of the synchronous copy system.