SIFT (Software Implemented Fault Tolerance) is an ultrareliable computer for critical aircraft control applications that achieves fault tolerance by the replication of tasks among processing units. The main processing units are off-the-shelf minicomputers, with standard microcomputers serving as the interface to the I/O system. Fault isolation is achieved by using a specially designed redundant bus system to interconnect the processing units. Error detection and analysis and system reconfiguration are performed by software. Iterative tasks are redundantly executed, and the results of each iteration are voted upon before being used. Thus, any single failure in a processing unit or bus can be tolerated with triplication of tasks, and subsequent failures can be tolerated after reconfiguration. Independent execution by separate processors means that the processors need only be loosely synchronized, and a novel fault-tolerant synchronization method is described. The SIFT software is highly structured. The correctness of SIFT is to be proved using a hierarchy of formal models. A Markov model is used both to analyze the reliability of the system and to serve as the formal requirement for the SIFT design. Axioms are given to characterize the high-level behavior of the system, from which a correctness statement has been proved. An engineering test version of SIFT is currently being built.

  • Corporate Authors:

    Institute of Electrical and Electronics Engineers (IEEE)

    3 Park Avenue, 17th Floor
    New York, NY  United States  10016-5997
  • Authors:
    • Wensley, J H
    • Lamport, L
    • Goldberg, J
    • Green, M W
    • Levitt, K N
    • Melliar-Smith, P M
    • Shostak, R E
    • Weinstock, C B
  • Conference:
  • Publication Date: 1978-10

Media Info

  • Features: References;
  • Pagination: p. 1240
  • Serial:
    • Volume: 66
    • Issue Number: 10

Subject/Index Terms

Filing Info

  • Accession Number: 00189726
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Apr 12 1979 12:00AM