What is Kafka Replication?
Replication provides fault tolerance by maintaining multiple copies of each partition across different brokers. Each partition has one leader and multiple followers (replicas).
What is a Partition Leader?
The Leader handles all read and write requests for a partition. Followers replicate from the leader. If the leader fails, one follower becomes the new leader (failover).
What are In-Sync Replicas (ISR)?
ISR are replicas that are currently alive and caught up with the leader. Only ISR replicas are eligible to become leaders. This ensures data consistency during failover.
What is the Unclean Leader Election?
When all ISR replicas are unavailable, this setting determines if a non-ISR replica can become leader (risking data loss) or if the partition remains unavailable until ISR recovers.
What is Log Retention?
Kafka retains messages for a configurable period (time-based) or size limit. Once retention limits are reached, old messages are deleted to free up disk space.
