Patent ID: 7917714

Claim:
A storage system comprising: a first storage system including a first volume; a second storage system including a second volume; and a third storage system including a third volume, wherein the first volume functions as a first primary volume storing data received from a first host computer, the second volume functions as a first secondary volume which is paired with the first volume and stores data received from the first storage system, and the third volume functions as a second secondary volume which is paired with the second volume and stores data received from the second storage system, and wherein, if a first host computer has a failure, the second volume functions as a second primary volume storing data received from a second host computer, the first volume functions as a third secondary volume which is paired with the second volume and stores data received from the second storage system, and the third volume functions as a fourth secondary volume which is paired with the second volume and stores data received from the second storage system.