Does min insync replicas property effects consumers in kafka

Question

I have configuration min.insync.replicas=2 and default.replication.factor=3 for my 3 node cluster. If I try to produce when only one broker is up it was failed as I expected. But If I try consume when only 1 broker is available the consumer is still able to consume messages. It seems min.insync.replicas=2 is not working for consumers. is it know behavior or I am missing anything ?

Answer 1

min.insync.replicas specifies the minimum number of replicas that must acknowledge a write in order to consider this write as successful and therefore, it has an effect on the producer side which is responsible for the writes. This configuration parameter does not have any direct impact on the consumer side and this is why it does not affect Consumers, even if the number of alive brokers is less than the value of min.insync.replicas.

According to the documentation,

When a producer sets acks to "all" (or "-1"), min.insync.replicas specifies the minimum number of replicas that must acknowledge a write for the write to be considered successful. If this minimum cannot be met, then the producer will raise an exception (either NotEnoughReplicas or NotEnoughReplicasAfterAppend). When used together, min.insync.replicas and acks allow you to enforce greater durability guarantees. A typical scenario would be to create a topic with a replication factor of 3, set min.insync.replicas to 2, and produce with acks of "all". This will ensure that the producer raises an exception if a majority of replicas do not receive a write.