Patent ID: 7076621

Claim:
A remote copy system comprising: a first computer; a plurality of first storage systems connected to said first computer; a second computer; and a plurality of second storage systems connected to a second computer; wherein: each of said plurality of first storage systems comprises a first storage unit and a first storage control unit connected to said first storage unit; each of said plurality of second storage systems comprises a second storage unit and a second storage control unit connected to said second storage unit; each of said plurality of first storage systems is coupled to one of said plurality of second storage systems; said first storage control unit receives a plurality of write requests including write times from said first computer, writes write data in each write request in said first storage unit in an order of the write request having an older write time, transmits a completion of a write process to said first computer, and transmits the write requests to said second storage control unit connected to said first storage control unit in an order of an older write time; said second storage control unit receives the write requests from said first storage control unit connected to said second storage unit, stores the write requests in a secondary update information storage unit possessed by said second storage control unit in the order of the older write time, and transmits a completion report to said first storage control unit connected to said second storage control unit; said second computer determines a standard time to be used for said second storage control unit to determine whether the write data in each write request is stored in said second storage unit, and also determines a subsidiary standard time which is the latest time from all times reported from all of the second storage systems when the standard time is determined; said second storage control unit writes the write data in each write request having a write time equal to or before said standard time; and said second storage control unit inquires to said first storage control unit as to whether it has received a new write request from the first computer, and, if the second storage control unit receives a notice from said first storage control unit which notice indicates that said first storage control unit did not receive a new write request from the first computer, the second storage control unit sends the subsidiary standard time to said second computer, so that said second computer can update the standard time.