A storage apparatus is provided in which the data amount of transfer data to a secondary disk controller from a primary disk controller at the event of remote copying can be reduced, and data integrity also can be assured. According to the storage apparatus, in the primary disk controller, overwriting update data in same records during a specified time between a preset first base point and a preset second base point on the update data that are stored in the second area of the cache memory and that are to be transferred to the secondary disk controller; and in the secondary disk controller, handling the update data between the first base point and the second base point as real data having consistency.