Comparison of hybrid modular redundant multiprocessor systems with respect to performabilities

A hybrid modular redundant (HMR) processor consists of VSD (Voter/Switch/Detector) module and computing modules. The authors discuss performability of three typical multiprocessor systems defined using HMR processors: (1) NSMS in which HMR processors share no computing module, (2) CSMS in which HMR processors share all computing modules, and (3) PSMS in which adjacent HMR processors share two computing modules. In order to evaluate reliability, the authors apply a combinatorial approach for NSMS and CSMS. On the other hand, for PSMS they first propose a reconfiguration algorithm, and then construct a layered Markov chain model based on the algorithm. Simulation results show that if VSD modules never fail, then performability of PSMS and CSMS are very high, but NSMS has the worst performability. It is also shown that if VSD modules may fail, then performability of PSMS almost does not change, but performability of CSMS falls down drastically. Therefore, one can conclude that PSMS has both high reliability and high performance with a reasonable cost.