Hi All, I am seeing strange behavior between ZK and Kafka. We have 5 node in ZK and Kafka cluster each. Kafka version - 2.11-0.10.1.1
The min.insync.replicas is 3, replication.factor is 5 for all topics, unclean.leader.election.enable is false. We have 15 partitions for each topic. The step we are following in our testing. * My understanding is that ZK needs aleast 3 out of 5 server to be functional. Kafka could not be functional without zookeeper. In out testing, we bring down 3 ZK nodes and don't touch Kafka nodes. Kafka is still functional, consumer\producer can still consume\publish from Kafka cluster. We then bring down all ZK nodes, Kafka consumer\producers are still functional. I am not able to understand why Kafka cluster is not failing as soon as majority of ZK nodes are down. I do see error in Kafka that it cannot connection to ZK cluster. * With all or majority of ZK node down, we bring down 1 Kafka nodes (out of 5, so 4 are running). And at that point the consumer and producer start failing. My guess is the new leadership election cannot happen without ZK. * Then we bring up the majority of ZK node up. (1st Kafka is still down) Now the Kafka cluster become functional, consumer and producer now start working again. But Consumer sees big junk of message from kafka, and many of them are duplicates. It's like these messages were held up somewhere, Where\Why I don't know? And why the duplicates? I can understand few duplicates for messages that consumer would not commit before 1st node when down. But why so many duplicates and like 4 copy for each message. I cannot understand this behavior. Appreciate some insight about our issues. Also if there are blogs that describe the ZK and Kafka failover scenario behaviors, that would be extremely helpful. Thanks, Shri This e-mail and its contents (to include attachments) are the property of National Health Systems, Inc., its subsidiaries and affiliates, including but not limited to Rx.com Community Healthcare Network, Inc. and its subsidiaries, and may contain confidential and proprietary or privileged information. If you are not the intended recipient of this e-mail, you are hereby notified that any unauthorized disclosure, copying, or distribution of this e-mail or of its attachments, or the taking of any unauthorized action based on information contained herein is strictly prohibited. Unauthorized use of information contained herein may subject you to civil and criminal prosecution and penalties. If you are not the intended recipient, please immediately notify the sender by telephone at 800-433-5719 or return e-mail and permanently delete the original e-mail.
