云计算:系统实例与研究现状

Cloud Computing:System Instances and Current Research

针对云计算这样一个范畴综述了当前云计算所采用的技术,剖析其背后的技术含义以及当前云计算参与企业所采用的云计算实现方案.云计算包含两个方面的含义:一方面是底层构建的云计算平台基础设施,是用来构造上层应用程序的基础;另外一方面是构建在这个基础平台之上的云计算应用程序.主要是针对云计算的基础架构的研究与实现状况给出综述,对于云计算的应用也有所涉及.云计算有3个最基本的特征:第1个是基础设施架构在大规模的廉价服务器集群之上;第二是应用程序与底层服务协作开发,最大限度地利用资源;第3个是通过多个廉价服务器之间的冗余,通过软件获得高可用性.云计算达到了两个分布式计算的重要目标:可扩展性和高可用性.可扩展性表达了云计算能够无缝地扩展到大规模的集群之上,甚至包含数千个节点同时处理.高可用性代表了云计算能够容忍节点的错误,甚至有很大一部分节点发生失效也不会影响程序的正确运行.通过此文可以了解云计算的当前发展状况以及未来的研究趋势.

This paper surveys the current technologies adopted in cloud computing as well as the systems in enterprises. Cloud computing can be viewed from two different aspects. One is about the cloud infrastructure which is the building block for the up layer cloud application. The other is of course the cloud application. This paper focuses on the cloud infrastructure including the systems and current research. Some attractive cloud applications are also discussed. Cloud computing infrastructure has three distinct characteristics. First, the infrastructure is built on top of large scale clusters which contain a large number of cheap PC servers. Second, the applications are co-designed with the fundamental infrastructure that the computing resources can be maximally utilized. Third, the reliability of the whole system is achieved by software building on top of redundant hardware instead of mere hardware. All these technologies are for the two important goals for distributed system： high scalability and high availability. Scalability means that the cloud infrastructure can be expanded to very large scale even to thousands of nodes. Availability means that the services are available even when quite a number of nodes fail. From this paper, readers will capture the current status of cloud computing as well as its future trends.