Patent ID: 7953947

Claim:
A storage system comprising: a first storage system including: a first volume which includes a first data area storing data sent from a computer and a first marker area storing a first marker which corresponds to the data stored in the first volume; and a first processor which stores data sent from the computer in the first volume; a second storage system including: a second volume which includes a second data area and a second marker area storing the first marker; a third volume; and a second processor which is configured to store data sent from the first storage system in the second volume; wherein the first processor transfers the data stored in the first data area of the first volume in the first storage system, to the second storage system, and the second processor stores the data in the second data area of the second volume, wherein after the first processor transfers the data stored in the first data area to the second storage system, the first processor transfers the first marker stored in the first marker area to the second storage system, and the second processor stores the first marker in the second marker area of the second volume, wherein the second processor checks whether transferring the data stored in the first data area and the first marker stored in the first marker area to the second storage system, is completed, wherein the second processor checks whether the first marker stored in the second storage area of the second volume corresponds to a second marker designated by the computer, and wherein, if transferring the data stored in the first data area and the first marker stored in the first marker area to the second storage system is completed and the first marker stored in the second storage are of the second volume is a second marker designated by the computer, the second processor creates a snapshot of the data that is stored in the second data area, in the third storage volume.