Log Replication#

// TODO

Rough Notes#

• Raft log replaces the WAL from stage 3
• Leader appends client operations to log, replicates to followers
• AppendEntries RPC with actual log entries
• Commit index (entry committed when replicated to majority)
• Apply committed entries to state machine (KV store)
• Log matching property (consistency across nodes)
• Fsync log entries before responding to client
• nextIndex and matchIndex tracking per follower
• Happy path only - no crashes/failures yet

Resources#

• The Raft Consensus Algorithm
• Distributed Systems 6.2: Raft by Martin Kleppmann
• Students’ Guide to Raft by Jon Gjengset
• Database Internals Chapter 14: Consensus by Alex Petrov
• Designing Data-Intensive Applications Chapter 5: Replication by Martin Kleppmann