Upgrade the Operating System

To upgrade the operating system (OS) on Confluent Platform hosts, upgrade clients and non-broker components first, then upgrade Apache Kafka® brokers one at a time. The procedure follows the same workflow as a standard Confluent Platform upgrade but does not require configuration changes like modifying the inter.broker.protocol.version.

Note

Confluent does not provide support for issues encountered during the operating system upgrade itself. Confluent recommends reaching out to your OS provider for any OS-specific issues.

Upgrade order

To reduce the impact of an OS upgrade, upgrade your Confluent Platform hosts in the following order.

  1. Clients and non-broker components: Start with the machines running Kafka clients, ksqlDB, Kafka Connect, and other components. The Kafka cluster backs these components, so issues during the OS upgrade have limited impact.

  2. Kafka brokers: Upgrade brokers last, one at a time. Issues on a broker can affect every downstream service.

Pre-upgrade checks

Before you take a broker down, confirm the cluster can tolerate the loss of one broker by verifying the min.insync.replicas setting on every topic.

Minimum in-sync replicas: Verify that min.insync.replicas is lower than your replication factor so the cluster stays available when one broker is down. For example, with replication factor 3, min.insync.replicas should be 2. Check the topic configuration with the following command:

kafka-configs --bootstrap-server <broker-host>:<port> --describe --entity-type topics --entity-name <topic-name>

Post-upgrade checks

After you upgrade the OS on a broker and restart the Confluent Platform services, perform these checks to verify that the broker has successfully rejoined the cluster and is functioning correctly:

Describe Topics: Use the kafka-topics --describe command to check the status of your topics.

kafka-topics --bootstrap-server <broker-host>:<port> --describe

Verify the following:

  • Under-Replicated Partitions (URPs): Ensure there are no under-replicated partitions.

kafka-topics --bootstrap-server <broker-host>:<port> --describe --under-replicated-partitions

  • In-Sync Replicas (ISR): Confirm that the broker you upgraded is in the ISR list for the partitions it hosts.

kafka-topics --bootstrap-server <broker-host>:<port> --describe --under-min-isr-partitions

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