Performing the Upgrade

Log in to Ambari.

Browse to Admin > Stack and Versions.

Click on the Versions tab.

Click Perform Upgrade.

Ambari will check that your cluster meets the prerequisites. A dialog will be presented with the results:

If any prerequisites are not met but are required, the result will be shown with an error. You will not be allowed to proceed with the upgrade. Make the appropriate corrections and return to Perform Upgrade again.
If any prerequisites are not met but are optional, the result will be shown with a warning. You will be allowed to Proceed with the upgrade.
A list of configuration changes (if any) will be displayed.

Once the prerequisite checks are complete, the upgrade will start. The time it takes to perform the upgrade dependents on many factors. As part of the upgrade process, each component in the cluster is restarted in a serial fashion so the stop/start time is a big contributor to the overall time.

The upgrade process involves a set of stages. This table lists the high-level stages and if the process requires any action by you during normal operation. Note: if any stage fails, the upgrade will halt and prompt for action.

Stage	Description	Action Required
Prepare Upgrade	This stage prepares HDFS and HBase for upgrade and reminds you to perform backups of your database for Hive, Oozie and Ranger.	You must acknowledge the prompt for database backups.
ZooKeeper	All ZooKeeper servers are upgraded and restarted.	None
Ranger	Ranger Admin and UserSync servers are upgraded and restarted.	None
Core Masters	This stage upgrades the master components of core services. This includes JournalNodes & NameNodes (HDFS), HistoryServer (MapReduce2), ResourceManager & ATS (YARN) and HBase Masters (HBase).	None
Service Checks	All Service Checks are performed against the cluster.	If any service check fails, you will be prompted to Ignore and Continue, Downgrade or Retry.
Core Slaves	This stage upgrades the slave components of core services. This includes DataNodes (HDFS), RegionServers (HBase) and NodeManagers (YARN). This is done in two batches: 20% of the slaves first, then the remaining slaves.	After the first 20% batch is complete, you will be prompted to Verify the cluster is operating correctly.
Service Checks	All Service Checks are performed against the cluster.	If any service check fails, you will be prompted to Ignore and Continue, Downgrade or Retry.
Hive	This stage upgrades the Hive Metastore, HiveServer2 and WebHCat components.	Ambari will switch the HiveServer2 port from 10000 to 10010 (or, 10011 if using HTTP transport mode). You will be prompted to confirm prior to the switch.
Spark	The Spark Job History Server and clients are upgraded.	None
Oozie	The Oozie Server and clients are upgraded.	None
Falcon	The Falcon Server and clients are upgraded.	None
Clients	All remaining clients are upgraded.	None
Service Checks	All Service Checks are performed against the cluster.	If any service check fails, you will be prompted to Ignore and Continue, Downgrade or Retry.
Kafka	The Kafka Brokers are upgraded.	None
Knox	The Knox Gateways are upgraded.	None
Storm	The Nimbus, REST API, DRPC Server and UI Server components are upgraded, along with the Supervisors.	None
Slider	The Slider clients are upgraded.	None
Flume	The Flume agents are upgrade.	None
Finalize	The component upgrades are complete. You are presented the option to Finalize, which when selected, completes the upgrade process + saves the cluster state.	Prompted to Finalize, Finalize Later or Downgrade.

Once the upgrade is complete, you have an option to Finalize the upgrade, to Finalize Later or to Downgrade. Finalizing later gives you a chance to perform more validation on the cluster. Downgrade moves the cluster version back to the previous version (basically: the reverse of the upgrade process stages). Once finalized, you cannot downgrade back to the previous version.

	Note
	If you choose to finalize later, both versions will be listed on the Stack and Versions tab with the starting version displaying as Current. It is not until you finalize that Ambari makes the target version the current version. Also, until you finalize, you will not be able to perform operational changes to the cluster (such as move components, change configurations, etc).

Click Finalize and the upgrade process is complete.

​Performing the Upgrade