Hello Luke, and thank you for your answer. What I would have hoped for is something more automatic, something that will spread the load when a Kafka broker goes down without any human intervention. The reassign script is a bit complicated, you need to generate the topics and partitions list, then get the current assignment and rework it to force a new leader.
On Tue, Nov 15, 2022 at 5:18 AM Luke Chen <show...@gmail.com> wrote: > Hi Pierre, > > Try using kafka-reassign-partitions.sh to reassign partitions to different > replicas you like. > ref: https://kafka.apache.org/documentation/#basic_ops_automigrate > > Luke > > On Mon, Nov 14, 2022 at 3:55 PM Pierre Coquentin < > pierre.coquen...@gmail.com> > wrote: > > > Hello, > > We have a Kafka cluster (2.4.1) with a replication factor of 3. I notice > > when we stop a broker that only one broker takes all the load from the > > missing broker and becomes the leader to all partitions. > > I would have thought that Kafka would split the load evenly among the > > remaining brokers. > > > > So if I have this kind of configuration > > Topic: test > > Partition 0 - Leader: 1 - Replicas: 1,2,3 - Isr: 1,2,3 > > Partition 1 - Leader: 2 - Replicas: 2,3,1 - Isr: 1,2,3 > > Partition 2 - Leader: 3 - Replicas: 3,1,2 - Isr: 1,2,3 > > Partition 3 - Leader: 1 - Replicas: 1,2,3 - Isr: 1,2,3 > > Partition 4 - Leader: 2 - Replicas: 2,3,1 - Isr: 1,2,3 > > Partition 5 - Leader: 3 - Replicas: 3,1,2 - Isr: 1,2,3 > > > > If I stop broker 1, I want something like this (load is split evenly > among > > broker 2 and 3): > > Topic: test > > Partition 0 - Leader: 2 - Replicas: 1,2,3 - Isr: 2,3 > > Partition 1 - Leader: 2 - Replicas: 2,3,1 - Isr: 2,3 > > Partition 2 - Leader: 3 - Replicas: 3,1,2 - Isr: 2,3 > > Partition 3 - Leader: 3 - Replicas: 1,2,3 - Isr: 2,3 > > Partition 4 - Leader: 2 - Replicas: 2,3,1 - Isr: 2,3 > > Partition 5 - Leader: 3 - Replicas: 3,1,2 - Isr: 2,3 > > > > What I observe is currently this (broker 2 takes all the load from broker > > 1): > > Partition 0 - Leader: 2 - Replicas: 1,2,3 - Isr: 2,3 > > Partition 1 - Leader: 2 - Replicas: 2,3,1 - Isr: 2,3 > > Partition 2 - Leader: 3 - Replicas: 3,1,2 - Isr: 2,3 > > Partition 3 - Leader: 2 - Replicas: 1,2,3 - Isr: 2,3 > > Partition 4 - Leader: 2 - Replicas: 2,3,1 - Isr: 2,3 > > Partition 5 - Leader: 3 - Replicas: 3,1,2 - Isr: 2,3 > > > > My concern here is that at all times, a broker should not exceed 50% of > its > > network bandwidth which could be a problem in my case. > > Is there a way to change this behavior (manually by forcing a leader, > > programmatically, or by configuration)? > > From my understanding, the script kafka-leader-election.sh allows only to > > set the preferred (the first in the list of replicas) or uncleaned > > (replicas not in sync can become a leader). > > Regards, > > > > Pierre > > >