lets assume there is a Kafka cluster with 4 Brokers (B1 - B4), and a Kafka Topic (T) with replication factor 2.
At first all replicas of T are on B1 and B2. Then, a partition reassignment is started that moves all of T’s replicas to brokers B3 and B4.
Is that reassignment “transparent” for any consumers and producers working with that topic?
Or is there a sort of down time in which no messages can be written to, or read from the topic?
I guess that moving only some (lets say half) of the partitions to the new brokers would make it so at least the other partitions can still be used by clients, but is that actually true? (or is the whole topic somehow “locked” for the duration of the reassignment?)
Thanks to anyone who can shed a bit of light on this