Software rejuvenation and runtime reliability monitoring

The overall system reliability of complex Cyber Physical systems is contributed both by hardware reliability and software reliability. The former can be often increased through fault-tolerant mechanisms and architectures, while the latter can take advantage of a suitable rejuvenation policy. These characteristics call for flexible runtime safety checks of system executions that go beyond conventional runtime mon-itoring of pre-programmed safety conditions, also in order to minimize maintenance costs. Defining a satisfying monitoring model for complex systems is still a challenge. In this paper, we investigate the application of a novel approach, named Reliability Based Monitoring (RBM), that allows for a flexible runtime monitoring of software reliability in complex systems. The approach leverages a hierarchical reliability model periodically applied to runtime diagnostics data: this allows to dynamically plan rejuvenation activities that are able to prevent software failures.