STORAGE SYSTEM AND STORAGE SYSTEM DATA MIGRATION METHOD

This storage system collectively manages a plurality of types of file groups reaching storage time limit, and carries out data migration spanning a plurality of storage devices. Based on the respective file information, of the respective files distributed among the respective volumes, files, whose storage time limit arrives within a prescribed period of time, are grouped together as a migration group. The storage term of the group is made to coincide with the file having the most distant storage time limit of the respective files. A first migration is carried out on the basis of the priority of the respective storage devices. A second migration is executed on the basis of the device life of the respective storage devices and the storage term of the group.