This, along with other interview questions on Hadoop admin, is a regular feature in Hadoop admin interviews, be ready to tackle it with the approach mentioned below. Upgrading a Hadoop cluster to a newer version can be a complex process and it depends on the current version and the target version, but some general steps that can be followed include:   Planning: Before upgrading, it is important to understand the changes and new features in the target version, and plan accordingly. This includes identifying any compatibility issues or deprecated features and making necessary adjustments to your data and applications.   Backup: Create a backup of your current Hadoop cluster, including all data, configurations, and metadata, to ensure that you can roll back if necessary.   Test: Test the upgrade process on a small test cluster before applying it to the production cluster. This will help identify any issues and make any necessary adjustments. 4.  Upgrade the cluster: Perform the upgrade by following the instructions provided by the vendor or the community. The process will depend on the current version and the target version, but it will typically involve upgrading the master nodes and then upgrading the worker nodes.   Validate: Once the upgrade is complete, validate the cluster's functionality and performance to ensure that everything is working as expected.   Monitor: Monitor the cluster for any issues and troubleshoot them in a timely manner.   Update your Applications: update your applications to the latest version if they are compatible with the new version of Hadoop.   Rollback: If the upgrade process failed or caused issues, you can roll back to the previous version using the backup.   Repeat the process: Repeat the process for all the Hadoop components like Hive, Pig, Hbase, etc.   Keep the documentation: Keep a detailed documentation of the upgrade process, including the version details, issues faced, and the resolution. This will be helpful for future reference and troubleshooting.