To provide a method and apparatus for migration of a storage subsystem without needing reconfiguration of an input/output path.

A first storage subsystem has a first port name for a first port, and a first volume inside the first storage subsystem performs input/output (I/O) connection with a computer device by a network through the port. A second storage subsystem defines a first virtual volume associated with the first volume and a first virtual port having a first virtual port name identical to the first port name. After activation of the first virtual port, the computer device switches the input/output (I/O) connection for the first volume from the first storage subsystem to the second storage subsystem via the network by use of the first virtual port name on the second storage subsystem.