I’m playing around with a simple 3-node cluster. I only have 7 topics, most with 10 partitions (one with 1, and another 25) and all replication factor of 2. I have ensured these partitions are spread amongst the Brokers. Most topics are set to “delete” and one to “compact”. Self-balancing is on and set to improve balance “anytime”. Like I say, simple.
Over time I can see in Control Center that the disc usage goes out of balance. Brokers 1 and 2 are at 4.8GB and 4.4GB respectively, but Broker 3 sits at 2.2GB. So something is up dspite the configuration being identical.
I have tried searching for information on how trace the problem, but it’s like looking for a needle in a haystack. I suspect it’s a problem with the Partition balance (Broker 3 seems to have about a third the partitions of the others in QA), but is this not what self-balancing is supposed to address?