3.1. Prerequisites

To perform a rolling upgrade, your cluster must meet the following prerequisites. If you do not meet these upgrade prerequisites, you can consider a Manual Upgrade HDP 2.2 to 2.3 of the cluster.

General

Requirement	Description
Current HDP Version	Must be running HDP 2.2 or later to perform a rolling upgrade. The rolling upgrade capability is not available for clusters running HDP 2.0 or 2.1.
Target HDP Version	All hosts must have the target version installed. See the Register Version and Install Version sections for more information.
Ambari Agent Heartbeats	All Ambari Agents must be heartbeating to Ambari Server. Any hosts that are not heartbeating must be in Maintenance Mode.
Host Maintenance Mode	Any hosts in Maintenance Mode must not be hosting any Service master components.
Service Maintenance Mode	No Services can be in Maintenance Mode.
Services Started	All Services must be started and the Service Check must pass.

HDFS

Requirement	Description
NameNode HA	NameNode HA must be enabled and working properly. See the Ambari User's Guide for more information, Configuring NameNode High Availability.
NameNode Truncate	HDP 2.2.6 introduced the NameNode Truncate option. Truncate must not be enabled.
Client Retry	HDFS client retry should be dfs.client.retry.policy.enabled

YARN

Requirement	Description
ResourceManager HA	YARN ResourceManager HA should be enabled to prevent a disruption in service during the upgrade. See the Ambari User's Guide for more information on Configuring ResourceManager High Availability.
Start Preserving Recovery	YARN start preserving recovery should be enabled. Check the Services > YARN > Configs property `yarn.timeline-service.recovery.enabled` .
Work Preserving Restart	YARN Work Preserving Restart must be configured. Check the Services > YARN > Configs property `yarn.resourcemanager.work-preserving-recovery.enabled` .

MapReduce 2

Requirement	Description
MapReduce Distributed Cache	MapReduce should reference Hadoop libraries from the distributed cache in HDFS. Refer to the YARN Resource Management guide for more information.
State Preserving Recovery	JobHistory state preserving recovery should be enabled.

Tez

Requirement	Description
Tez Distributed Cache	Tez should reference Hadoop libraries from the distributed cache in HDFS.

Hive

Requirement	Description
Multiple Hive Metastore	Multiple Hive Metastore instances are recommended for Rolling Upgrade. This ensures that there is at least one Hive Metastore running during the upgrade process.
Hive Dynamic Service Discovery	HiveServer2 dynamic service discovery is recommended for Rolling Upgrade.
HiveServer2 Port	During the upgrade, Ambari will switch the HiveServer2 port from 10000 to 10010 (or 10011 if using HTTP transport mode).
Hive Client Retry	Hive client retry properties must be configured. Review the Services > Hive > Configs configuration and confirm `hive.metastore.failure.retries` and `hive.metastore.client.connect.retry.delay` are specified.

Oozie

Requirement	Description
Oozie Client Retry	Oozie client retry properties must be configured. Review the Services > Oozie > Configs > oozie-env configuration and confirm `"export OOZIE_CLIENT_OPTS="${OOZIE_CLIENT_OPTS} -Doozie.connection.retry.count=<number of retries>"` is specified.

If you do not meet the upgrade prerequisite requirements listed above, you can consider a Manual Maintenance Upgrade of the cluster.

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