Patent ID: 8356157

Claim:
A storage system, comprising: a plurality of storage devices; a controller controlling to read/write of a first type data from/to the plurality of storage devices; wherein the controller is configured to manage a plurality of virtual volumes and a storage pool, the storage pool corresponding to a plurality of logical volumes provided with a plurality of storage areas in the plurality of storage devices, wherein the controller is configured to determine, for each virtual volume of the plurality of virtual volumes, a formatting type of the virtual volume based on a pattern of writes from a host to the virtual volume, and to determine whether each received data for each virtual volume is first type data that is data to be written to a virtual storage area of the virtual volume after formatting the virtual volume or second type data that is management information for formatting the virtual volume based on the formatting type determined by the controller for the virtual volume, wherein the controller is configured to allocate, if a received data is of the first type data and targeted to a virtual storage area of a first virtual volume of the plurality of virtual volumes, a storage area in the storage pool to the virtual storage area of the first virtual volume as a data storage area if allocation is necessary, and to write the received data of the first type data to the storage area allocated as the data storage area, wherein the controller is configured to allocate, if the received data is of the second type data and targeted to the virtual storage area of the first virtual volume of the plurality of virtual volumes, a storage area in the storage pool to the virtual storage area of the first virtual volume as a management information storage area if allocation is necessary, and to write the received data of the second type data to the storage area allocated as the management information storage area, and wherein a quantity of storage areas to be allocated to the first virtual volume for writing data of the first type data is greater than a quantity of storage areas to be allocated to the first virtual volume for writing data of the second type data.