分布式一致性算法Raft论文（2）——复制状态机

2 Replicated state machines

集群中某些服务器不可用，整个集群还可以工作。

算法保证安全性；

复制日志保持顺序性；

        Consensus algorithms typically arise in the context of replicated state machines [37]. In this approach, state machines on a collection of servers compute identical copies of the same state and can continue operating even if some of the servers are down. Replicated state machines are used to solve a variety of fault tolerance problems in distributed systems. For example, large-scale systems that have a single cluster leader, such as GFS [8], HDFS [38],and RAMCloud [33], typically use a separate replicated state machine to manage leader election and store configuration information that must survive leader crashes. Examples of replicated state machines include Chubby [2] and ZooKeeper [11].

        共识算法通常出现在复制状态机的上下文中[37]。在这种方法中，服务器集合上的状态机计算相同状态的相同副本，即使某些服务器关闭，整个集群也可以继续运行。复制状态机用于解决分布式系统中的各种容错问题。例如，具有单个集群领导者的大型系