Reliability and high availability have always been a major concern in distributed systems. Providing highly available and reliable services in cloud computing is essential for maintaining customer confidence and satisfaction and preventing revenue losses. Although various solutions have been proposed for cloud availability and reliability, but there are no comprehensive studies that completely cover all different aspects in the problem. This paper presented a ‘Reference Roadmap’ of reliability and high availability in cloud computing environments. A big picture was proposed which was divided into four steps specifying through four pivotal questions starting with ‘Where?’, ‘Which?’, ‘When?’ and ‘How?’ keywords. The desirable result of having a highly available and reliable cloud system could be gained by answering these questions. Each step of this reference roadmap proposed a specific concern of a special portion of the issue. Two main research gaps were proposed by this reference roadmap.

中文翻译：

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云计算环境中的可靠性和高可用性：参考路线图

可靠性和高可用性一直是分布式系统中的主要问题。在云计算中提供高可用性和可靠的服务对于维持客户的信心和满意度以及防止收入损失至关重要。尽管已针对云的可用性和可靠性提出了各种解决方案，但是还没有全面涵盖问题中所有不同方面的综合研究。本文提出了云计算环境中可靠性和高可用性的“参考路线图”。提出了一个大图，该图分为四个步骤，以“ Where？”，“ Which？”，“ When？”开头的四个关键问题指定。如何？' 关键字。通过回答这些问题，可以获得具有高度可用和可靠的云系统的理想结果。该参考路线图的每个步骤都提出了对该问题特殊部分的特殊关注。该参考路线图提出了两个主要的研究空白。