Software fault tolerance in real-time systems

Abstract The paper proposes a technique for providing software fault tolerance in real-time applications demanding fast response and a high degree of reliability. It is shown that a reasonably flexible interprocess communication can be supported with only a small increase in complexity and overhead. The two most prominent features of the proposed scheme are (1) it attempts to exploit fault-avoidance techniques as much as possible to reduce the overhead of fault tolerance and (2) it controls the propagation of errors so as to enable efficient recovery. Formal proofs of the system operation are developed. Besides showing that the scheme works as expected, the arguments serve to highlight the assumptions needed for provably correct operation. Some issues relating to hardware fault tolerance are also considered.