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]](../common/images/admon/important.png) | Important |
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For a Kerberized cluster, you must review and configure your KDC:
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For any Cluster
- Disk Space
Be sure to have adequate space on
/usr/hdpfor 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.
- KDC Admin Credentials
The Ambari Server will add new components as part of the HDP 2.6 to HDP 3.0 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 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.
- 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.
- 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+.
Next Steps
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