Before you can upgrade Apache Knox, you must have first upgraded your HDP components to the latest version (in this case, 2.4.0). This section assumes that you have already upgraded your components for HDP 2.4.0. If you have not already completed these steps, return to Getting Ready to Upgrade and Upgrade 2.1 Components for instructions on how to upgrade your HDP components to 2.4.0.

When working with the Knox Gateway in your Hadoop cluster, it is important you have the latest version of Knox installed so you can take advantage of new features and enhancements, in addition to ensuring your instance of Knox is in sync with other Hadoop components (e.g. Ranger, Spark, Hive, Hue, etc.) for stability and performance.  For example, if you need to upgrade your Hadoop cluster from 2.1 to 2.2.x, you should also make sure that your individual Hadoop components are also upgraded to the latest version.

HDP enables you to perform a rolling upgrade in 2.2.x. A rolling upgrade means that you can upgrade a component, or the entire Hadoop stack, without losing service, and your users can continue to use the cluster and run jobs with no application or server downtime. The main distinction between a rolling upgrade and a traditional upgrade implies the use of a Knox cluster for high availability capabilities. This means that you can require multiple instances of the gateway and a load balancer serving each gateway instance from a single URL.

The main distinction between a rolling upgrade and a traditional upgrade implies the use of a Knox cluster for high availability capabilities. This means that you can require multiple instances of the gateway and a load balancer serving each gateway instance from a single URL. Once the upgrade process is completed, you will be up and running with the latest version of Knox on each server you have designated as a Knox server.

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	In this document, whenever you see a {} with a value inside, this denotes a value you must define.