Patent ID: 7958326

Claim:
A storage system comprising: a main volume that is a logical volume in which an update is generated by writing a data element transmitted from a higher-level device; a copy storage area that is a storage area in which a data element prior to updating in said main volume is copied; a snapshot management unit that manages a correspondence between a plurality of virtual storage positions in a snapshot volume that is a virtual logical volume for logically holding a snapshot image of said main volume and a plurality of address information elements indicating a plurality of actual storage positions of a plurality of data elements constituting the snapshot image of the main volume that are stored in said main volume and/or said copy storage area; a full backup unit that executes a full backup that is a backup of differential management information and data elements from all the storage positions indicated by said plurality of address information elements to a backup destination storage device; a differential management unit that updates differential management information for managing which virtual storage position within said snapshot volume is equivalent to a difference when the difference occurs between said snapshot volume and said backup destination storage device due to updating of said snapshot volume following an update of said main volume after said full backup; and a partial backup unit that executes a partial backup in which an actual storage position of one or more data elements equivalent to the difference between said snapshot volume and said backup destination storage device is specified from an address information element corresponding to a virtual storage position specified from said differential management information, and the differential management information and one the one or more data elements present in the specified actual storage position are backed up to said backup destination storage device.