Chapter 2. Getting Ready to Upgrade Ambari and HDP

When preparing to upgrade Ambari and the HDP Cluster, we strongly recommend you review this checklist of items to confirm your cluster operation is healthy. Attempting to upgrade a cluster that is operating in an unhealthy state can produce unexpected results.

	Important
	If planning to upgrade Ambari and upgrade to a new HDP minor version (for example: moving from HDP 2.1 to HDP 2.2), upgrade Ambari to the lastest version before upgrading the cluster. Refer to the Stack Compatibility Matrix to see which HDP versions each Ambari version supports.

Ensure all services in the cluster are running.
Run each Service Check (found under the Service Actions menu) and confirm they execute successfully.
Clear all alerts, or understand why they are being generated. Remediate as necessary.
Confirm start and stop for all services are executing successfully.
Time service start and stops. The time to start and stop services is a big contributor to overall upgrade time so having this information handy is useful.
Download the software packages prior to the upgrade. Place them in a local repository and/or consider using a storage proxy since multi-gigabyte downloads will be required on all nodes in the cluster. Refer to Using a Local Repository for more information.

Ensure point-in-time backups are taken of all DBs supporting the clusters. This includes (among others) Ambari, Hive Metastore, Ranger and Oozie.

	Note
If you upgraded Ambari from 2.0x to 2.1x, you must make sure that the Ranger db root password is NOT set to blank before performing any Stack upgrade. Ambari 2.1x requires that the Ranger db root password has a value. If you upgrade Ambari to 2.1x and upgrade the stack without setting a value for the Ranger db root password, Ranger Admin will fail to start after the upgrade. To prepare Ranger for upgrades, set the password for the Ranger DB root user to a non-blank value. Then, set the Ranger db root password field in Ambari Web to match this value. Finally, restart Ranger Admin using Ambari Web.

Note

If you upgraded Ambari from 2.0x to 2.1x, you must make sure that the Ranger db root password is NOT set to blank before performing any Stack upgrade. Ambari 2.1x requires that the Ranger db root password has a value. If you upgrade Ambari to 2.1x and upgrade the stack without setting a value for the Ranger db root password, Ranger Admin will fail to start after the upgrade.

To prepare Ranger for upgrades, set the password for the Ranger DB root user to a non-blank value. Then, set the Ranger db root password field in Ambari Web to match this value. Finally, restart Ranger Admin using Ambari Web.

For Ambari Upgrades

This (Ambari 2.1) Upgrade Guide will help you upgrade your existing Ambari install to version 2.1. If you are upgrading to another Ambari version, please be sure to use the Ambari Upgrade Guide for that version.
Be sure to review the Known Issues and Behavioral Changes for this Ambari release in the Ambari 2.1.2 Release Notes.

For HDP Cluster Upgrades

Ensure sufficient disk space on /usr/hdp/<version> (roughly 3GB for each additional HDP release).
If you plan to add new services available with HDP to your cluster, the new services might include new service accounts. Any operational procedures required to support these new service accounts should be performed prior to the upgrade. The accounts will typically be required on all nodes in the cluster.
If your cluster includes Storm, document any running Storm topologies.

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