Storage system, data relocation method thereof, and recording medium that records data relocation program

Abstract

There is a need to improve access speed for a file in a storage system that is provided with multiple storage units having different access speeds. The storage system () includes an access frequency acquiring part () that divides a past constant accessed data acquisition period into multiple unit periods, and obtains an access frequency for file stored in any of the multiple storage units (and), a similarity degree calculating part () that obtains, for each file, a similarity degree between the access frequency to the file for each unit period, and the access frequency to every other file for each unit period, a grouping process part () that groups one or more other files having a similarity degree equal to or higher than a predetermined value, in an identical group, and a file relocation part () that places a file belonging to the identical group into a storage unit () having a high access speed, when the file stored in the storage units (and) is accessed and there exists any other file within the identical group to which the file belongs.