Digital data processor with improved backup storage

Abstract

An improved backup storage system and method for use in conjunction with hierarchical or mass storage servers and networks is disclosed. Baseline, full and incremental backup procedures are used to save file copies. In one preferred embodiment, the baseline backup procedure is used to store copies of stable files, i.e. files that are modified less frequently, if at all. With a hierarchical storage server, such files are typically those stored on tertiary storage media, e.g. erasable optical disks, WORMs or magnetic tape. The full backup procedure stores, as full backup copies, copies of all files not in the baseline backup and files that have been changed since the time of their baseline backup. The full backup procedure also stores file identifiers and signal representative of storage locations of baseline backup copies for files which have not been changed since the time of the baseline backup. The incremental backup procedure stores, as incremental backup copies, copies of files not in the baseline or full backups, e.g., new files, and files that have changed since the time of their last backup (baseline, full or incremental). The incremental backup procedure also stores file identifiers and signals representative of storage locations of baseline backup copies for files which have not been changed since the time of the baseline backup, and also stores file identifiers and signals representative of storage locations of full and incremental backup copies for files which have not been changed since the time of their full or incremental backup.