Cloud computing has been increasingly concerned in scientific computing area. More and more enterprises and research institutes have migrated their applications to the clouds. Due to the complexity of cloud computing system in structural and behavioral aspects, how to design the fault tolerant cloud computing system becomes a challenging problem. This paper investigates the modeling and analysis of fault tolerant strategy for deadline constrained task scheduling in cloud computing. First, a formal description language is defined to accurately model the different components of cloud application, and use it to characterize the operational mechanisms and fault behaviors. Second, we propose a fault tolerant strategy, which includes the scheduling mechanism, synchronization mechanism, and exception mechanism, to dynamically compute the execution mode and required virtual machine for tasks, thus ensuring the reliability and real-time requirement of cloud application. An enforcement algorithm is also designed to realize the proposed strategy. Third, the techniques of Petri nets are provided to analyze and validate the correctness of proposed method. Finally, several experiments are done to illustrate that the reliability of cloud application is improved and its deadline is met.

中文翻译：

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云计算中限期约束任务调度的动态容错策略建模与分析

云计算在科学计算领域越来越受到关注。越来越多的企业和研究机构将应用迁移到云端。由于云计算系统在结构和行为方面的复杂性，如何设计容错的云计算系统成为一个具有挑战性的问题。本文研究了云计算中限期约束任务调度容错策略的建模和分析。首先，定义了一种形式化描述语言，以准确地对云应用程序的不同组件进行建模，并用它来表征运行机制和故障行为。其次，我们提出了容错策略，包括调度机制、同步机制和异常机制，动态计算任务的执行方式和所需的虚拟机，从而保证云应用的可靠性和实时性要求。还设计了一种强制算法来实现所提出的策略。第三，提供了Petri网的技术来分析和验证所提出方法的正确性。最后，通过几个实验来说明云应用的可靠性得到了提高，并且满足了它的期限。