Technology

RAFT

RAFT is the consensus algorithm that ensures a cluster of servers (e.g., 3-of-5 quorum) maintains a consistent, replicated log, simplifying fault-tolerant distributed systems like etcd and CockroachDB.

RAFT is the de-facto consensus protocol for strongly consistent distributed systems, designed by Diego Ongaro and John Ousterhout to be more understandable than its predecessor, Paxos. The protocol operates by decomposing consensus into three clear subproblems: Leader Election, Log Replication, and Safety. A single elected leader manages all client requests and log replication across the cluster. Log entries are committed only after a majority (a quorum) of servers has replicated them, ensuring fault tolerance: a 5-server cluster, for example, can tolerate two failures. This leader-based architecture provides the foundation for critical infrastructure like etcd and CockroachDB.