Kafka · easy · ~8 min
Same incident, now hands-on. Broker kafka-3 is down and 6 partitions are under-replicated. Producers are still writing (min.insync.replicas is met). Take actions and watch the cluster telemetry respond. Get to a healthy state — UnderReplicated = 0 with no data loss — in as few moves as possible. Some actions look tempting but trade away data you can't get back.
kafka-3
min.insync.replicas
UnderReplicated = 0