consensus bridging theory and practice

derstandability. Raft first elects a server as leader, then concentrates all decision-making onto the

leader. These two basic steps are relatively independent and form a better structure than Paxos,

whose components are hard to separate. Raft elects a leader using voting and randomized timeouts.

The election guarantees that the leader already stores all the information it needs, so data only flows

outwards from the leader to other servers. Compared to other leader-based algorithms, this reduces

mechanism and simplifies the behavior. Once a leader is elected, it manages a replicated log. Raft

leverages a simple invariant on how logs grow to reduce the algorithm’s state space and accomplish

this task with minimal mechanism.

well enough for practical deployments, and it addresses all aspects of building a complete system,

is easier for students to learn than Paxos. The algorithm has been formally specified and proven,

its leader election algorithm works well in a variety of environments, and its performance is equiv-

alent to Multi-Paxos. Many implementations of Raft are now available, and several companies are

deploying Raft.