Patent ID: 6922763

Claim:
A method of managing backup and restoring of data between a plurality of copy volumes in a storage system, each of said copy volumes originating from a single volume and configuring a pair with said single volume, each of said copy volumes capable of being independently used, said managing method comprising: when said volumes configuring each said pair are used by separate applications, storing, for each said pair in a memory, an address at which updating of data has been made in said volumes as updated-location-managing information; in case a copy volume configuring a first pair is to be restored to have the contents of a copy volume belonging to a second pair, obtaining, from said memory, pieces of said updated-location-managing information for each of said first and second pairs; generating differential information by merging said pieces of updated-location-managing information obtained, said differential information indicative of a difference in said pieces of updated-location-managing information between the copy volumes; and reproducing said copy volume which is to be restored to have the contents of said copy volume to be the source of restoring, by copying data designated by said differential information from said copy volume to be the source of restoring to said copy volume which is to be restored.