Patent ID: 8533415

Claim:
A system comprising: a plurality of servers including a first server located on a first data center, the first server configured to implement a plurality of virtual servers on each of which an operating system (OS) is run; a first storage system, coupled to the plurality of servers of the first data center via a first switch, located on the first data center, the first storage system including a plurality of storage devices and a first controller configured to manage a logical area provided by the plurality of storage devices; a plurality of servers located on a second data center, the plurality of servers of the second data center configured to implement a plurality of virtual servers on each of which an OS is run; and a second storage system, which is coupled to the plurality of servers of the second data center via a second switch and the first storage system, located on the second data center, the second storage system including a plurality of storage devices and a second controller configured to manage a logical area provided by the plurality of storage devices, wherein the first controller is configured to copy updated data of a first logical area of the logical area, which is related to the first virtual server, of the first storage system to a second logical area of the logical area of the second storage system which is a copy pair of the first logical area, wherein the first controller is configured to copy, when the virtual servers on the first data center are migrated from the first server to a second server of the plurality of second servers, differential data between the first logical area and the second logical area so that the first virtual server is implemented by the second server on the second data center, wherein the virtual servers provided by the first server are migrated to the servers on the second data center after completion of the migration of the first logical area, and wherein the first server is powered off if migration of the plurality of virtual servers on the first server are completed.