重配置与周期再生相结合的软件再生模型

Software Rejuvenation Model Based on Reconfiguration and Periodical Rejuvenation

针对持续运行软件系统中的老化问题,提出一种重配置与周期再生相结合的软件再生方法.采用连续时间马尔可夫链对两阶段衰退软件系统的工作模式进行建模,给出系统可用性和单位时间平均成本的形式化定义与分析,并以可用性和成本作为评价标准计算相应的最佳再生周期,推导出了采用重配置的临界条件.仿真结果表明,随着重配置成功率的提高,系统的可用性增加,成本降低,当重配置成功率为1时,与纯周期再生方法相比,采用结合重配置的软件再生方法可使系统单位时间宕机成本降低48.9%.

To counteract the phenomenon of software aging and system failures,a software rejuvenation model based on reconfiguration is proposed.The continuous time Markov chain is adopted to describe the rejuvenation model for software systems with two degradation states.The formal definition and analysis of the system availability and of the expected total cost per unit time are given.The optimal rejuvenation interval is obtained by either maximizing the availability or minimizing the expected cost.A reconfiguration threshold is derived by comparing the rejuvenation method based on reconfiguration with the periodical rejuvenation method.Simulation results show that the system availability increases and the downtime cost decreases as the success probability of the reconfiguration increases.A comparison with the periodical rejuvenation method shows that when the success probability of the reconfiguration is 1,the system downtime cost is reduced by 48.9%.