Duplicate data obtained by copying and a volume containing it are flexibly managed according to the attribute of the file to be copied by a storage apparatus as is required by a user. When receiving a backup instruction for the file to be backed up, an instruction for a method managing the attribute of the object to be backed up and the duplicate data obtained by the backup of the object to be backed up is also received. In this case, the duplicate data and the volume name to store it are related, thereby managing the specified attribute.