A comparison-based model for system-level fault diagnosis thatgeneralizes both the classical PMC model and the Maeng/Malek comparisonmodel is studied. A new necessary and sufficient condition for a systemto be t-diagnosable under this model is proven. Also, a class of systemsthat uses the minimum number of communication links to obtain a givendegree of diagnosability is presented. Next, a distributed diagnosisalgorithm is presented that can reduce the number of tests necessary fordiagnosis when the number of faults is relatively small. To demonstratethe practicality of our diagnosis approach, a fault table baseddiagnosis algorithm suitable for relatively small systems has beenimplemented in the Common Spaceborne Multicomputer Operating System(COSMOS). A simulator for the JPL MAX multicomputer system runningCOSMOS was used to test the algorithm and evaluate its performance. Theresults show that the algorithm diagnoses all fault situations with lowlatency and very little overhead
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