Storage network arrangements effecting a method including: acquiring information on the real volumes, and port information on the physical devices in which the real volumes reside; creating virtual volumes being linked to the real volumes, based on the information on the real volumes; forming one or more virtual volume groups by combining the virtual volumes, based on the port information, in such a way that the virtual volumes and the virtual volume groups in which the virtual volumes reside have a virtual-volume-to-virtual-volume-group configuration which is identical to a real-volume-to-physical-device configuration of the real volumes and the physical devices in which the real volumes reside; and establishing the created virtual volume groups in the upper storage apparatus.