Raft
also: consensus algorithm · Paxos
The understandable consensus algorithm — how a cluster agrees on one log despite crashes.
Raft gets a cluster to agree on an ordered log of commands: elect a leader (randomized timeouts), replicate entries to followers, commit once a majority acknowledges. Designed as the teachable alternative to Paxos, it runs etcd, Consul and most modern coordination layers. Rule of thumb: consensus for the small critical state (locks, leaders, membership), not the data path.