Incremental computer file backup using a two-step comparison of first two characters in the block and a signature with pre-stored character and signature sets

Patent 5794254 Issued on August 11, 1998. Estimated Expiration Date:

December 3, 2016. 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

3711863

3715734

Automatic centralized monitoring system
Patent #: 4361832
Issued on: 11/30/1982
Inventor: Cole

Automatic fault detection and recovery system which provides stability and continuity of operation in an industrial multiprocessor control
Patent #: 4377000
Issued on: 03/15/1983
Inventor: Staab

Data compression process
Patent #: 4491934
Issued on: 01/01/1985
Inventor: Heinz

High speed data compression and decompression apparatus and method
Patent #: 4558302
Issued on: 12/10/1985
Inventor: Welch

System memory for a reduction processor evaluating programs stored as binary directed graphs employing variable-free applicative language codes
Patent #: 4616315
Issued on: 10/07/1986
Inventor: Logsdon , et al.

Method for communicating changes made to text form a text processor to a remote host
Patent #: 4641274
Issued on: 02/03/1987
Inventor: Swank

Memory back-up system
Patent #: 4654819
Issued on: 03/31/1987
Inventor: Stiffler , et al.

Database backup method
Patent #: 4686620
Issued on: 08/11/1987
Inventor: Ng

More ...

Inventor

McClain, Fred W.

Assignee

Fairbanks Systems Group

Application

No. 757134 filed on 12/03/1996

US Classes:

707/204, Archiving or backup707/10, Distributed or remote access707/202, Recoverability711/111, Accessing dynamic storage device711/162, Backup714/6Redundant stored data accessed (e.g., duplicated data, error correction coded data, or other parity-type data)

Examiners

Primary: Amsbury, Wayne
Assistant: Pardo, Thuy N.

Attorney, Agent or Firm

Rogitz; John L.

Foreign Patent References

0541281A2 EP. 05/23/1993
WO 94/17474 WO. 08/23/1994

International Class

G06F 017/00

Abstract

A system backs up computer files to a remote site via modem. Files of a user computer that are found in a common library at the remote site initially are not copied to the remote site, whereas files not in the library are copied to the remote site. Then, periodically the user computer determines which blocks have been changed, and the user computer transmits only changed blocks to the remote site. The blocks are gathered in "chunk" files, and when a chunk file reaches a predetermined size, it is transmitted to the remote site for updating the back up version of the respective file. The process then resumes identifying changed blocks. In addition to flagging the changed block for transfer, the process resynchronizes the local data file with the backed up version using a two-step comparison, first comparing the first two characters in the block with a pre-stored character set, and then, if the first comparison results in a match, comparing a digital signature of the changed block with a pre-stored signature. If either comparison results in a mismatch, the test is repeated using, as the first byte of the test block, the next byte in the sequence.

Other References

Article: "Distributed Network Processing Speeds Up Network Backup." Masters. 8211 Computer Technology Review. vol. 10, pp. 55-56-58-60. Aug. 1992
Article: "Exploiting Symmetries For Low-Cost Comparison of File Copies." Barbara et al. The 8th International Conference on Distributed Computing Systems. The Computer Society. IEEE CH2541-1/88. pp. 471-479. Jun. 13, 1988
Brochure: 3Com Corp. 3165 Kifer Road, Santa Clara, CA 95052. 3+ Network Software Family. 29 pages. Sep. 1991
Brochure: Emerald Systems. 12230 World Trade Drive, San Diego, CA 92128. NetWare 3.11 Compatible product line and price list. 18 pages. Jun. 199