A fault-tolerant system experiences a crash due to hardware components' faults or progressive performance degradation as an "aging"  phenomenon,  because of running continuously for very long periods.  This paper considers both hardware components' faults and "aging"  phenomenon, proposes composing redundant structure and rejuvenation schedule in the fault-tolerant system, formalizes the system with Non-Markovian stochastic Petri nets,  and evaluates quantitatively the performance of a system based on this model.