Patent ID: 7437389

Claim:
A system comprising: a plurality of first storage devices each connected to a host computer; and a plurality of second storage devices each connected to any of the first storage devices, wherein each of said plurality of first storage devices is configured to hold the processing of a write request received from the host computer based on the instruction from a management unit and to restart thereafter the processing of the write request received from the host computer based on the instruction from said management unit; each of said plurality of first storage devices is configured to manage as a write data set the write data of the write request processed after the processing of the write request has been restarted according to the instruction from said management unit till the processing of the write request is then held according to the instruction from said management unit; said management unit is configured to receive a completion report of holding the processing of the write request from said plurality of first storage devices and then to instruct said plurality of first storage devices to create new write data sets, to attach common identification information to the write data set created in said plurality of first storage devices, and then to instruct said plurality of first storage devices to restart the processing of the write request; and each of said plurality of second storage devices is configured to store the write data received from the first storage device for each write data set in logical volumes of said second storage devices and said plurality of second storage devices store the write data of the write data set having the same identification information in logical volumes of said second storage devices based on the instruction from said management unit.