Patent ID: 7424590

Claim:
A storage system that stores multiple copies of data by storing data written by a host apparatus to one or more primary logical volumes, both in the primary logical volumes and in one or more secondary logical volumes paired with the primary logical volumes, the storage system comprising: a first primary allocation unit for managing one or more first pool volumes, each being constituted from a portion of a storage area provided by corresponding storage devices and associated with one or more of the primary logical volumes, and allocating a dynamically variable storage area to the primary logical volumes from within the storage area managed as the associated first pool volume; a first secondary allocation unit for managing one or more second pool volumes, each being constituted from a portion of a storage area provided by corresponding storage devices and associated with one or more of the secondary logical volumes, and allocating a dynamically variable storage area to the secondary logical volumes from within the storage area managed as the associated second pool volume; a second primary allocation unit for allocating, in accordance with the status of storage area allocation to the primary logical volumes from within the storage area managed as the associated first pool volume, a dynamically variable storage area to the first pool volumes from within the storage area provided by the corresponding storage devices; and a second secondary allocation unit for allocating, together with the storage area allocation to the first pool volumes by the second primary allocation unit, a storage area to the second pool volumes from within the storage area provided by the corresponding storage devices, wherein the second primary allocation unit, if it has found all storage areas in the first pool volumes to be storage areas allocated from within the storage area provided by the storage devices, allocates, from within the unallocated storage area provided by the storage devices, a storage area to one or more first pool volumes, from among the first pool volumes, to which a storage area needs to be allocated, and wherein, together with the storage area allocation to the first pool volumes by the second primary allocation unit, the second secondary allocation unit allocates, from within the unallocated storage area provided by the corresponding storage devices, a storage area to one or more second pool volumes, from among the second pool volumes, that are directly associated with the first pool volumes.