Patent ID: 8706961

Claim:
A storage apparatus which is connected via a network to a host computer which requests data writing, comprising: storage media of a plurality of types of varying performance; a volume management unit configured to manage storage areas provided by the storage media of the plurality of types as different storage tiers and manage storage tiers of a same type or different types as a pool, and provide predetermined areas of the pool to the host computer as volumes; and a file management unit configured to construct file systems, for managing data in file units configured from a plurality of blocks, in the volumes, and receive file unit data write requests from the host computer and store the data into the volumes, wherein, among a plurality of the file systems, the file management unit is configured to migrate data in block units in one of the file systems in the volumes or migrate data in file units in the other of the file systems, based on a preconfigured user policy stored in the file management unit, and wherein the preconfigured user policy includes a condition for selecting the file unit migration or the block unit migration.