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Preparing to upgrade Cassandra

To prepare for Cassandra upgrade

  1. Ensure that all Cassandra nodes are ready. Run the following command and verify that all nodes are Up and Normal:
    nodetool status
  2. Leave the Cassandra service running but stop all Teamwork Cloud services.
  3. Back up your current database before upgrading.
  4. Upgrade all Cassandra data tables to current version by running the following command:
    nodetool upgradesstables

    This process can take a long time for large databases. Use the jobs option to use more threads for the operation (0 for maximum threads available, default is 2). Also, use the nohup command to run the upgrade process in the background.

    nohup nodetool upgradesstables --jobs 0 &

    Make sure this process is completed before proceeding!

Upgrading Cassandra

To upgrade Cassandra

  1. IMPORTANT! Flush memtables to the disk by executing the following command:

    nodetool drain

  2. Stop the Cassandra service.

  3. Make a note of the existing cluster name and token count with the following command:

    grep -E 'num_tokens:|cluster_name:' cassandra.yaml

  4. Uninstall/remove Cassandra (example with yum package manager)

    sudo yum remove -y cassandra

    Cassandra configuration files are saved with .rpmsave extension after uninstallation (default path: /etc/cassandra/default.conf). Archive these files for future reference.

  5. Install new version of Cassandra (for installation instructions, see Installing Cassandra on Linux).

  6. Check the cluster name and token count in cassandra.yaml. If needed, replace the default values with the values set in the previous version. The example below shows the default values for a Cassandra installation.

    cluster_name: 'Test Cluster'
num_tokens: 16

    The cluster name and token count must match those values set in the previous version of Cassandra.

  7. Start the Cassandra service.

  8. Check if the service is running smoothly:

    • Check the log file for startup errors.

    • Verify that all nodes have a status of Up and Normal with this command:

      nodetool status
  9. Upgrade all Cassandra data tables to current version by running the following command:
    nodetool upgradesstables

    This process can take a long time for large databases. Use the jobs option to use more threads for the operation (0 for maximum threads available, default is 2). Also, use the nohup command to run the upgrade process in the background.

    nohup nodetool upgradesstables --jobs 0 &

    Make sure this process is completed before proceeding!


Additional resources

For more information about upgrading Apache Cassandra, see https://www.datastax.com/learn/whats-new-for-cassandra-4/migrating-cassandra-4x.