What are the differences in the classification and implementation methods of the two consistency consensus algorithms?

This paper discusses the classification and implementation differences between two mainstream consensus algorithms. At present, consistency algorithms in distributed systems are mainly divided into two categories: single-point writing algorithm based on Leader and multi-point writing algorithm with peer. They vary in architecture, performance and applicable scenarios.

1. Single point write consistency algorithm based on Leader

The core of this type of algorithm is that a single Leader node is responsible for all write operations. Other nodes (Followers) are responsible for data synchronization and reading. Leader nodes ensure data consistency. This method is simple and easy to understand and has high writing efficiency, but a single point of failure of the Leader node will affect the writing capability of the entire system.

Typical implementations include Master-slave replication of MySQL and Master-slave mode of Redis. The Leader node receives all write requests and synchronizes the data to the Follower node to ensure data consistency.

2. Peer multi-point write consistency algorithm

Unlike the former, in the peer multi-point writing algorithm, all nodes have equal status and can write operations. The success of the write operation requires certain conditions to be met, such as all nodes or more than half of the nodes confirm that the write is successful. This ensures stronger system consistency and high availability, but has relatively low write efficiency and greater communication overhead.

Raft and Paxos algorithms are typical representatives of this type of algorithm and are widely used in distributed systems such as etcd and ZooKeeper. These algorithms ensure data consistency through collaborative work between nodes.

Summarize:

The two algorithms have their own advantages. The Leader-based algorithm is more suitable for scenarios where there are high requirements for write performance and tolerate a small amount of data loss; while the peer multi-point writing algorithm is more suitable for scenarios where there are extremely high requirements for data consistency and high availability. Which algorithm to choose depends on the specific application requirements and system design goals.

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