Virtualization method and storage apparatus for a storage system having external connectivity

A virtualization method for a storage system recognizes one or more logical devices located in a first and second storage apparatus and defined in a host apparatus as being connected to a channel, based on an inquiry command sent from the host apparatus when the channel comes on-line; detects one or more logical devices among the one or more logical devices defined in the host apparatus as being connected to the channel and located in the first and second storage apparatus, based on the recognition result; sets, based on the detection result, one or more virtual volumes in the first storage apparatus, respectively corresponding to the one or more logical devices in the second storage apparatus; and sets a first logical path between each of the set one or more virtual volumes and each of the corresponding one or more logical devices in the second storage apparatus.