Patent ID: 7707373

Claim:
A storage system comprising a plurality of storage devices of a sequential access type, the storage devices operable to process a sequential access at a high speed, but unable to process a random access at a high speed, and at least one storage device of a random access type operable to process a random access faster than said storage devices of a sequential access type, and in which data located in a logical volume on said at least one storage device of a random access type are backed up in said storage devices of a sequential access type, said storage system comprising: a full backup section operable to execute a full backup causing all data located in said logical volume to be backed up from said logical volume to a sequential device group comprising said plurality of storage devices of a sequential access type; a differential management information storage section operable to store differential management information, the differential management information being information representing a difference between said logical volume and said sequential device group after said full backup; a differential management section operable to updates said differential management information in response to an update of said logical volume; and a partial backup section operable to execute a partial backup by which partial data that are data equivalent to a difference between said logical volume and said sequential device group are specified by using said updated differential management information, information necessary for restoration that is necessary to restore a data group located in said updated logical volume by using said partial data is recorded in said sequential device group, and said partial data are backed up from said updated logical volume to said sequential device group, and further comprising: a backup management storage section operable to store backup unit management information representing, as a backup unit, a storage area of said sequential device group, that has been consumed by a backup to said sequential device group, and a backup unit management section operable to add, to said backup unit management information, information representing, as one backup unit, the storage area that has been consumed by said backup when said full backup or said partial backup is completed, wherein said backup unit management section comprises, for each backup unit, a backup unit identifier, a backup class representing a class of backup, and a sequence information representing a sequence of backup in said backup unit management information, and said partial backup section is operable to specify a backup unit having recorded therein backup of data necessary for restoration of said partial backup based on the sequence information and backup class in said backup unit management information and comprises a backup unit identifier of said specified backup unit and a backup class indicating that this is a partial backup in said information necessary for restoration.