A topic ’recurring payments’ is created on a Kafka cluster with three brokers (broker id...

With min.insync.replicas=3 and acks=all, a partition must have at least 3 in-sync replicas (ISRs) for the producer to succeed. With one broker down (broker 0), only 2 ISRs remain → not enough to meet the requirement. Therefore, producers cannot write to affected partitions.

However, for some partitions where the leader and replicas are on brokers 1 and 2, the full ISR (3) may still be present (if broker 0 was not a replica). In this scenario, exactly 6 of the 9 partitions may still have ISR=3 depending on replica distribution.

From Kafka documentation:

“When acks=all and min.insync.replicas is not met, the broker will reject the produce request with an exception.”

Page Reference:

Kafka: The Definitive Guide, 1st Edition, Chapter 5, p. 159–161

Apache Kafka Documentation: Topic Config – min.insync.replicas