The Internet world is moving toward a scenario where users and applications have very diverse service expectation, making the current best-effort model inadequate and limiting. To be able to design high-availability service systems, it is essential to consider not only the actual failure and recovery behavior of the service infrastructure, but also the behavioral aspects of its user and their subjective perceptions and reactions in the wake of failure events. In this paper, we propose to use Markov regenerative process (MRGP) models to study the availability of Internet-based services perceived by a Web user on two different online service scenarios: (1) single-user-single-host and (2) single-user-multiple-host. The MRGP models capture the interactions between the service facility and the user. We also detect its parameter bottlenecks by applying the formal sensitivity analysis technique. The trends of the users’ perceived unavailability are analyzed with the changed different parameter values, and the necessity of the sophisticated MRGP modeling is evidenced by the comparisons with the corresponding continuous time Markov chain (CTMC) models, which show that the popular convenient CTMC models tend to overestimate user-perceived service unavailability. Finally, controlled experiments are carried out on a real Web service to demonstrate the proposed approach.

中文翻译：

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用于用户感知可用性和瓶颈的 Web 服务器的马尔可夫再生模型

互联网世界正在走向一个场景，用户和应用程序对服务的期望非常不同，这使得当前的尽力而为模型变得不充分和限制。为了能够设计高可用性服务系统，不仅要考虑服务基础设施的实际故障和恢复行为，还要考虑用户的行为方面以及他们对故障事件后的主观感知和反应。在本文中，我们建议使用马尔可夫再生过程（MRGP）模型来研究 Web 用户在两种不同的在线服务场景中感知到的基于 Internet 的服务的可用性：（1）单用户单主机和（2）单用户多主机。MRGP 模型捕捉服务设施和用户之间的交互。我们还通过应用正式的敏感性分析技术来检测其参数瓶颈。通过改变不同的参数值分析用户感知不可用的趋势，并通过与相应的连续时间马尔可夫链（CTMC）模型的比较证明了复杂的 MRGP 建模的必要性，这表明流行的便捷 CTMC 模型倾向于高估用户感知的服务不可用性。最后，在一个真实的 Web 服务上进行了受控实验来演示所提出的方法。与相应的连续时间马尔可夫链 (CTMC) 模型的比较证明了复杂 MRGP 建模的必要性，这表明流行的便捷 CTMC 模型倾向于高估用户感知的服务不可用性。最后，在一个真实的 Web 服务上进行了受控实验来演示所提出的方法。与相应的连续时间马尔可夫链 (CTMC) 模型的比较证明了复杂 MRGP 建模的必要性，这表明流行的便捷 CTMC 模型倾向于高估用户感知的服务不可用性。最后，在一个真实的 Web 服务上进行了受控实验来演示所提出的方法。