Prerequisites

To perform an HDP upgrade using Ambari, your cluster must meet the following prerequisites. Meeting these prerequisites is essential for Ambari to know the cluster is in a healthy operating mode and can successfully manage the upgrade process.

Important

	Important
For a Kerberized cluster, you must review and configure your KDC: KDC Admin Credentials The Ambari Server will add new components as part of the HDP 2.6 to HDP 3.1 upgrade and needs to be configured to enable password encryption and saving the KDC admin credentials so necessary principals can be created. For steps on how to do this, see Encrypt Database and LDAP Passwords in Ambari and Managing Admin Credentials. KDC Admin Host FQDN Ensure that the KDC Admin host is set to a fully qualified domain name (FQDN) and not an IP address. You can check this setting by going to Services > Kerberos > Configs > KDC Hosts. KDC kadmin principal The MIT KDC integration in Ambari 2.7 has been improved to connect more securely with the Kerberos Administration server (kadmind). This increased security expects a Kerberos admin service principal to be present with a specifically formatted principal name. The format expected is `kadmin/fully.qualified.kdc.hostname@REALM`. This expectation is a behavior change from previous versions of Ambari, where having such a Kerberos admin service principal was not required. This principal is present by default in most MIT KDC installations, but some customers have reported that this principal does not exist in their KDC. Due to this, it's recommended that before upgrading a kerberized cluster to Ambari 2.7, you ensure this principal exists in your KDC database.

For a Kerberized cluster, you must review and configure your KDC:

KDC Admin Credentials

The Ambari Server will add new components as part of the HDP 2.6 to HDP 3.1 upgrade and needs to be configured to enable password encryption and saving the KDC admin credentials so necessary principals can be created. For steps on how to do this, see Encrypt Database and LDAP Passwords in Ambari and Managing Admin Credentials.

KDC Admin Host FQDN

Ensure that the KDC Admin host is set to a fully qualified domain name (FQDN) and not an IP address. You can check this setting by going to Services > Kerberos > Configs > KDC Hosts.

KDC kadmin principal

The MIT KDC integration in Ambari 2.7 has been improved to connect more securely with the Kerberos Administration server (kadmind). This increased security expects a Kerberos admin service principal to be present with a specifically formatted principal name. The format expected is kadmin/fully.qualified.kdc.hostname@REALM. This expectation is a behavior change from previous versions of Ambari, where having such a Kerberos admin service principal was not required.

This principal is present by default in most MIT KDC installations, but some customers have reported that this principal does not exist in their KDC. Due to this, it's recommended that before upgrading a kerberized cluster to Ambari 2.7, you ensure this principal exists in your KDC database.

For any Cluster

Disk Space

Be sure to have adequate space on /usr/hdp for the target HDP version. Each complete install of an HDP version will occupy about 5 GB of disk space.

Ambari Agent Heartbeats

All Ambari Agents must be communicating and heartbeating to Ambari Server. Any hosts that are not heartbeating must be in Maintenance Mode.

Hive Upgrade

The upgrade process does not back up the Hive MetaStore, nor does it compact ACID tables. Before upgrading Hive, you must:

Manually make a manual backup of your Hive metastore database after using the pre-upgrade tool, described later, and before upgrading.
If you have ACID tables in your Hive metastore, enable ACID operations using Ambari Web or set Hive configuration properties to enable ACID.

Host Maintenance Mode

The following two scenarios are checked:

Any hosts in Maintenance Mode must not be hosting any Service Master Components.
Any host in Maintenance Mode that is not hosting Master Components is allowed but you will receive a warning. You can proceed with your upgrade but these hosts will not be upgraded and before you can finalize the upgrade, you must delete the hosts from the cluster.

Service Maintenance Mode

No Services can be in Maintenance Mode, except for Ambari Metrics System, SmartSense, and Log Search.

Services Started

All Services must be started, except for Ambari Metrics System, SmartSense, and Log Search.

Service Checks

All Service Checks must pass. Be sure to run Service Actions > Run Service Check on all services (and remediate if necessary) prior to attempting an HDP upgrade.

All Prior Upgrades are Finalized

Any prior upgrade started with Ambari must be finalized.

Apache Zeppelin Notebooks and Configuration File Storage

In releases of Zeppelin earlier than HDP-2.6.3, notebooks and configuration files were stored on the local disk of the Zeppelin server. In HDP-2.6.3+, the default Zeppelin storage is HDFS.

When upgrading to HDP-2.6.3+ from versions earlier than HDP-2.6.3, perform the steps described in Enabling HDFS Storage for Zeppelin Notebooks and Configuration in HDP-2.6.3+.

Configure SSL after upgrading HDP 3.1.5.

During the HDP stack upgrade, the existing configurations are merged with the default configurations of the upgraded HDP stack.

If you are using default locations for keystores or truststores, move them to different non-default location and change the property values accordingly. For more information on the list of affected properties, see Apache Ambari Release Notes, known issues.

Next Steps

Prepare to Upgrade

More Information

Remove Service

​Prerequisites

Prerequisites