【摘要】介绍了提供高可用性的双机系统的原理、部署和体系结构；定义了双机系统各部件功能，描述了子系统间的接口，给出了该双机系统的有限自动机。该自动机具有有限数目的内部状态，模拟了双机系统的工作原理及内部各状态的相互转化，描述了服务切换、进程与服务监控、心跳侦测、网络参考点侦测等过程，为双机系统的行为描述和结构设计提供了理论依据和论证。关 键 词 双机系统; 有限自动机; 进程与服务监控; 心跳侦测; 网络参考点侦测; 服务切换Dual-hosts sytem providing high availability(HA) , which is the one of most important method for data integrity and service continuous, is widely required for user.The principle, deployment and framework of a dual-hosts system is introduced, and a turing machine of the dual-hosts system is presented in this paper.The turing machine simulates the dual-hosts system and describes the states transition of the dual-hosts system and supplies a theory basis for designing architecture of the dual-hosts system.