Patent ID: 7010650

Claim:
A multiple data management method in a system in which a host computer and primary and secondary storage devices are connected as capable of communicating with each other via a network, said primary and secondary storage devices functioning as data storage of said host computer, said method comprising: transmitting, by said host computer, data to be written and a write request Wa to said primary storage device in writing of data into said primary storage device and transmitting, by said host computer, said data to be written and a write request Wb to said secondary storage device at any point in time after said foregoing transmission; storing said data to be written by said primary storage device upon receipt of said write request Wa; storing said data to be written by said secondary storage device upon receipt of said write request Wb; wherein said data transmitted by said host computer to said secondary storage device is not received from said primary storage device by said host computer; said host computer attaching a serial number to said write request Wb transmitted to said secondary storage device, said serial number being given in an order of transmission of said write requests Wb; said secondary storage device storing said serial numbers attached to said write requests Wb, monitoring whether or not there is any missing serial number and, when a missing serial number is detected, transmitting to said host computer a data retransmission request of said data to be written corresponding to said missing serial number; upon receipt of said data retransmission request, said host computer transmitting said data to be written to said secondary storage device corresponding to said missing serial number; and said secondary storage device storing said data to be written upon receipt thereof.