<p>A path is formed between a host computer and storage apparatuses without depending on the configuration of the host computer and a network and a plurality of volumes having a copy function are migrated between storage apparatuses while keeping the latest data. A computer system includes a host computer and first and second storage apparatuses, wherein the second storage apparatus virtualizes a plurality of migration source volumes as a plurality of migration destination volumes and provides them to the host computer; and if the second storage apparatus receives an input/output request for each migration destination volume, it reflects data in each migration source volume via each migration destination volume and the host computer cancels a path to each migration source volume and registers a path to each migration destination volume; and if the second storage apparatus receives a write request, it writes write data to each migration destination volume and each migration source volume and migrates copy processing control information and data until the termination of migration processing.</p>
