Patent ID: 8250317

Claim:
A storage system comprising: a plurality of sub-storage systems, each of the sub-storage systems being coupled to a host, a sub-storage system of the plurality of sub-storage systems comprising: a first interface unit being coupled to the host via a first network, and for receiving a data input/output request from the host; a storage apparatus including a plurality of storage devices; a control unit that executes processing for inputting/outputting data to/from the storage apparatus in response to a data input/output request from a host that received the data by the first interface; a transmission control device that controls data input/output by coupling the control unit with the storage apparatus; and a second interface unit being coupled to a management apparatus via the second network, wherein the storage system further comprises: a coupling unit that couples at least two sub-storage systems of the plurality of sub-storage systems; and an integrated management unit being configured with the management apparatus, or with a plurality of management apparatuses, coupled to each of the sub-storage systems, wherein the integrated management unit manages by operating the plurality of sub-storage systems coupled to each other as a single access target for the host, manages by unifying a plurality of system administrator accounts and pieces of control information regarding the plurality of sub-storage systems, and manages, if there is a pool extending across both of storage areas provided by the storage apparatuses in the plurality of sub-storage systems, the pool in accordance with volume control information, wherein when the plurality of sub-storage systems are coupled to each other to form a loosely-coupled configuration, each sub-storage system searches for an unused resource within itself, and when the unused resource within itself is not sufficient and cannot be allocated, another sub-storage system having a sufficient resource is selected and can be allocated, and wherein when the plurality of sub-storage systems are coupled to each other to form a tightly-coupled configuration, any unused resource is allocated without regard to an identity of the sub-storage system.