Patent ID: 8032729

Claim:
A computer system comprising: a host computer: a first storage device coupled to the host computer, and including a plurality of first hard disk drive (HDDs) configuring to a plurality of volumes; a second storage device coupled to the first storage device, and including a plurality of second HDDs configuring to a plurality of volumes, different from the plurality of volumes of the first storage device; wherein two or more of the plurality of volumes in the first storage device are configured to a plurality of primary logical volumes storing write data from the host computer, and another at least one of the plurality of volumes in the first storage device are configured to at least one of transfer volumes storing the write data with a update number of the write data and with information about addresses on the plurality of primary logical volumes updated by the write data; wherein the first storage device transfers the write data with the update number of the write data and with information about the addresses on the plurality of primary logical volumes updated by the write data, in the at least one of transfer volumes to the second storage device, wherein two or more of the plurality of volumes in the second storage device are configured to a plurality of auxiliary logical volumes, which store replication data of the plurality of primary logical volumes, wherein the second storage device updates the plurality of auxiliary logical volumes with retaining the update order using the write data, according to the transferred write data with the update number of the write data and with the information about the addresses on the plurality of primary logical volumes updated by the write data, wherein the host computer retains a transfer volume management information including HDD identifiers corresponding to the plurality of primary volumes and identifiers of the at least one of the transfer volumes, wherein, from the plurality of volumes in the first storage device, the host computer extracts an additional transfer volume, corresponding to HDD which is different from the HDD corresponded to the at least one of the transfer volumes, if the capacity usage of the at least one of the transfer volumes reaches or goes above a predetermined level, wherein the host computer transmits an allocation request about the additional transfer volume, wherein, after receiving the allocation request, the first storage device enables a parallel operation of an HDD corresponding to the additional transfer volume and an HDD corresponding to the at least one of transfer volumes for transfer of write data to the second storage device.