System and apparatus for merging a write event journal and an original storage to produce an updated storage using an event map

摘要

A method and apparatus for restoring an updated computer storage from a journal of write events and a copy of an original storage generates an event map from the journal of write events. The event map permits efficient combination of the contents of the write event journal and the original storage. The event map also enables translation of the event journal into a delta expressing the differences between the original and updated storages. The event map similarly permits efficient merging of a write event journal and an original file stored streaming tape.