Chapter 3. Upgrading the Cluster

In this stage, services will be switched to the new software version.

	Important
	Perform all upgrade steps in the exact sequence listed in this section, for components deployed in your cluster.

Upgrade Zookeeper
Upgrade Ranger (if Ranger is enabled on your cluster)
Upgrade core-cluster master processes, including HDFS JournalNodes and NameNode, YARN ResourceManager, and HBase Master(s)
Upgrade core-cluster slave processes: HDFS DataNodes, YARN NodeManagers, and HBase RegionServers
Upgrade non-core cluster components: Hive, Oozie, and Falcon
Upgrade Knox
Upgrade components outside of the cluster, such as Storm topologies that run on Storm standalone
Upgrade Slider
Upgrade clients on cluster (core and non-core) components, such as MapReduce, Tez, and Phoenix client
Finalize the rolling upgrade process. Caution: rollback and rolling downgrade operations are not possible after this step!

After upgrading each component, you’ll validate that the component is running successfully.

	Note
	The `hdp-select` script requires root access. The instructions in this section assume that you start the upgrade process logged on as root.