BIB-VERSION:: CS-TR-v2.0
          ID:: STAN//CSL-TR-71-24
       ENTRY:: December 01, 1994
ORGANIZATION:: Stanford University, Computer Systems Laboratory
       TITLE:: AN IMPROVED RELIABILITY MODEL FOR NMR
        TYPE:: Technical Report
      AUTHOR:: Siewiorek, Daniel P.
        DATE:: December 1971
       PAGES:: 41
    ABSTRACT:: The classical reliability model for N-modular redundancy
               (NMR) assumes the network to be failed when a majority of
               modules which drive the same voter fail. It has long been
               known that this model is pessimistic since there are
               instances, termed compensating module failures, where a
               majority of the modules fail but the network is nonfailed. A
               different module reliability model based on lead reliability
               is proposed which has the classical NMR reliability model as
               a special case. It is shown that the standard procedure for
               altering the classical model to take compensating module
               failures into account may predict a network reliability which
               is too low in some cases and too high in others. It is also
               demonstrated that the improved model can increase the
               predicted mission time (the time the system is to operate at
               or above a given reliability) by 50% over the classical model
               prediction for a simple network.
       NOTES:: [Adminitrivia V1/Prg/19941201]
         END:: STAN//CSL-TR-71-24