Raft coordinates replicated state among controllers by committing an update only after a majority of followers acknowledge it. In Kafka’s KRaft architecture, controllers store cluster metadata in Raft logs, while brokers retrieve and serve that metadata to clients. section 9.1.1
The architecture establishes several important boundaries:
- Only controllers participate in the metadata quorum and write the metadata log; brokers may keep read-only local copies. section 9.1.1
- A newly elected controller leader has all committed entries, avoiding committed-data loss after leader change. section 9.1.1


