In KRaft, all cluster metadata is stored in a special internal Kafka topic: __cluster_metadata. Every change (broker registration, topic creation, partition reassignment) is appended as a metadata record. The active controller is the single writer. Brokers subscribe to this topic and maintain an in-memory metadata image. This enables instant metadata reads without ZooKeeper round-trips.
Key configuration
metadata.log.dir — separate directory for metadata log (recommended)
metadata.log.segment.bytes=1073741824 — metadata segment size