Fault tolerant computer backup system

Patent 5089958 Issued on February 18, 1992. Estimated Expiration Date:

February 18, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

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Inventors

Assignee

Vortex Systems, Inc.

Application

No. 300469 filed on 01/23/1989

US Classes:

714/5Of memory or peripheral subsystem

Examiners

Primary: Atkinson, Charles E.

Attorney, Agent or Firm

Ingersoll; Buchanan, Alstadt; Lynn J.

International Class

G06F 011/16

Abstract

A method and apparatus for storing and retrieving any prior state of a computer system is provided. Upon installation of the system, a base image corresponding to the initial state of the computer system is established and stored on a storage device. The system monitors changes to the state of the host and subsequently stores at least some of these changes on the storage device. These changes are then mapped by location of the stored changes in an address table to enable subsequent retrieval of any selected changes. When the address table becomes full, at least one differential image of the state of the system is subsequently created by compiling all changes to the base image which occurred between creation of the base image and the selected time. A virtual image may thus be created of data stored on the storage device, as such data existed at a predetermined prior point in time, from which data and files may be retrieved and written to the host disk.