A virtual storage apparatus based on a plurality of storage apparatuses including a first storage apparatus and a second storage apparatus is provided to a host computer. A first logical unit of the first storage apparatus and a second logical unit of the second storage apparatus are provided to the host computer in a form of a virtual logical unit. The first storage apparatus is configured to return a response to an inquiry about port statuses from the host computer designating the virtual logical unit, the response indicating that the status of the first port is a status as indicated by the first port management information and the second storage apparatus is unavailable to respond to the inquiry about port statuses. The second storage apparatus is configured to return no response to the inquiry.