Patent ID: 8205051

Claim:
A storage system comprising: a first storage system including a first plurality of disk drives and a first controller managing the first plurality of disk drives as a first volume; a second storage system including a second plurality of disk drives and a second controller managing the second plurality of disk drives as a second volume; and a third storage system including a third plurality of disk drives and a third controller managing the third plurality of disk drives as a third volume, wherein the storage system has a first status and a second status, wherein, in the first status: the first volume stores data received from a first host computer, the second volume is configured as a first copy pair with the first volume and stores copy data received from the first storage system, and the third volume is configured as a second copy pair with the second volume and stores data received from the second storage system, and wherein, in the second status: the second volume stores data received from a second host computer, the first volume configures a third copy pair with the second volume and stores data received from the second storage system, the third volume is configured as a fourth copy pair with the second volume and stores data received from the second storage system.