Patent ID: 7454582

Claim:
An initial copy system for remote copy, comprising: a plurality of computer systems at a plurality of sites, each of said computer systems includes external devices and storage apparatuses coupled to the external devices, respectively, the storage apparatuses at the plurality of sites being coupled to each other through a communication network, wherein data in a first storage apparatus of the storage apparatuses at a first site of the sites being remotely copied into a second storage apparatus of the storage apparatuses at a second site of the sites; and a third storage apparatus, initially connected to the first storage apparatus at the first site, which is subsequently disconnected from the first storage apparatus and then moved to the second site so as to be connected to the second storage apparatus at the second site, said third storage apparatus being an external storage apparatus with respect to the first and second storage apparatus, wherein the first, second and third storage apparatuses each comprises a logical device formed by a plurality of disk drives, external device managing information for defining a configuration of an external storage device, and a control unit, wherein the control unit of the first storage apparatus generates a snapshot of the logical device of the first storage apparatus in the logical device of the third storage apparatus and recognizes the logical device in the third storage apparatus as the logical device of the third storage apparatus, wherein the control unit in the first storage apparatus generates and manages a bit map indicating difference data between copy target data derived from the snapshot and updated data of copy target data and updates the external device managing information in the first storage apparatus, when the third storage apparatus is disconnected from the first storage apparatus, said third storage apparatus is then subsequently moved to the second site and connected to said second storage apparatus at the second site, wherein the control unit in the second storage apparatus recognizes the logical device in the third storage apparatus as a copy target of a remote copy and updates the external device managing information in the second storage apparatus, when the third storage apparatus is connected to the second storage apparatus at the second site after having been disconnected from the first storage apparatus at the first site and moved to the second site so as to be connected to the second storage apparatus at the second site, and wherein the control unit of the first storage apparatus controls writing performed by the control unit, of the second storage apparatus on the difference data in the bit map transmitted through the communication network in the logical device recognized by the second storage apparatus so as to accord the data in the second storage apparatus with the data in the first storage apparatus.