Patent ID: 8375000

Claim:
A remote copy system comprising: at least one host computer, a plurality of first storage systems, a plurality of second storage systems each of which is coupled to one of the plurality of first storage systems, respectively, and a plurality of third storage systems each of which is coupled to one of the plurality of second storage systems, respectively, wherein each of the first storage systems comprises a first control section and a storage area providing a first logical volume, wherein each of the second storage systems comprises a second control section and a storage area providing a second logical volume, wherein each of the third storage systems comprises a third control section, a storage area providing a third logical volume and a third storage area, wherein each of the first control sections stores data of a write request from the host computer to the first logical volume, and sends a completion notification to the host computer after receiving a notice from the second control section that the data is stored in the second logical volume, respectively, wherein the host computer: A) sends instructions for deferment of a write request processing to all of the first control sections of the plurality of the first storage systems, B) sends a marker instruction to all of the second control sections after receiving completion reports of the deferment from all of the first control sections, C) sends instructions for release of the deferment of the write request processing to all of the first control sections after receiving completion reports of the marker instruction from all of the first control sections, and D) repeats the steps A, B, and C, while incrementing the marker number included in the marker instruction each time the marker instruction is sent, wherein each of the second control sections transfers a plurality of write data associated with a marker, which is included in the latest marker instruction at the time when it is received, to one of the third storage systems, wherein one of the host computers determines which marker is made at the earliest time among the markers received by all of the second storage systems and instructs all of the third control sections to store the transferred plurality of write data that is associated with the marker previous to the determined marker, and wherein the each of the third control sections stores the data, transferred from the second control section, to the third storage area and restores the data to the third logical volume.