METHODS AND SYSTEMS FOR STORAGE SYSTEM GENERATION AND USE OF DIFFERENTIAL BLOCK LISTS USING COPY-ON-WRITE SNAPSHOTS

摘要

Methods and systems for generating differential backup or roll forward data within a storage system. Snapshot copies are generated within the storage system using copy-on-write techniques to maintain the integrity of the snapshots so generated. As an atomic operation with the generation of any snapshot, a copy of the list of data saved by the copy-on-write operations in any earlier snapshots is retained with the newly generated snapshot. The saved overwritten data list and any pair of corresponding snapshots may then be used to generate an accurate differential block list for data to be included in a differential backup or in a roll forward operation. Thus a storage system may generate differential backups or roll forward updates by its own processing to relieve attached host systems from the processing burden.