I was performing a rolling kafka broker upgrade from 2.2.1 to 3.2.0(from cp 5.2.2 to 7.2.1).This was done as a rolling upgrade on kafka cluster.There are three pods i.e, kafka-0,kafka-1 and kafka-2.The replication factor for this topic is 2.During this rolling upgrade I am facing a downtime as leader is not assigned for "test" partition.
Cannot get leader of topic test partition 4: kafka server: In the middle of a leadership election, there is currently no leader for this partition and hence it is unavailable for writes
when I added log I can see Partition leader=-1
I tried increasing the replication factor for one of the topic it worked but no concrete reason why did that happen
Probably you have min.in.sync.replicas=2, and unclean.leader.election=false. Therefore, when the current leader went down, it wasn't fully replicated, so no other replica will take its place.
You have 3 brokers, so there's no reason not to have replication factor of 3, other than to save cost, with the tradeoff of unavailability when losing any one replica.