Failure and Coverage Factors Based Markoff Models: A New Approach for Improving the Dependability Estimation in Complex Fault Tolerant Systems Exposed to SEUs

Dependability estimation of a fault tolerant computer system (FTCS) perturbed by single event upsets (SEUs) requires obtaining first the probability distribution functions for the time to recovery (TTR) and the time to failure (TTF) random variables. The application cross section (sigmaAP) approach does not give directly all the required information. This problem can be solved by means of the construction of suitable Markoff models. In this paper, a new method for constructing such models based on the system's failure and coverage factors is presented. Analytical dependability estimation is consistent with fault injection experiments performed in a fault tolerant operating system developed for a complex, real time data processing system.