Applying simulation to the design and performance evaluation of fault-tolerant systems

The paper illustrates how the CESIUM simulation tool can be used for design and performance evaluation of fault tolerant and real time systems, in addition to testing the correctness of protocol implementations. We calibrate three increasingly accurate simulation models of a network of workstations using independently obtained data. For a sample group membership protocol, the predictions of the simulator are very close to the actual performance measured in the real system. We also apply CESIUM to the evaluation of two potential improvements for the protocol, performing experiments that would have been difficult to implement in the real system. The results of the simulations give us valuable insight on how to tune configuration parameters, as well as on the performance gains of the improved versions. Our experience shows that CESIUM can be used to develop best effort services which adapt their quality of service according to the failures that occur during operation.