Patent ID: 8239644

Claim:
A control device of a storage system that comprises a plurality of storage devices including a first type of storage device, comprising: a memory which stores an archive deadline of archive target data which are a target of archiving by the storage system, and a warranty deadline which is a quality warranty deadline of parity groups configured by two or more of the first type of storage device; a controller which stores the archive target data in the parity groups configured by two or more of the first type of storage device, and wherein the memory stores unit costs constituting costs for a predetermined storage size of the storage device and data migration costs constituting costs required for data migration from a certain storage device among the storage devices of a plurality of types, to another storage device among the storage devices of the plurality of types; wherein the controller calculates archive costs constituting costs for a case where the archive target data are stored in the parity group for each parity group based on the unit costs and the data migration costs, wherein the control device sequences parity groups to store the archive target data based on the archive cost and a length between the warranty deadline of a parity group and the archive deadline of the archive target data.