Turn off Auto Restart from Ambari Web by browsing to Admin > Service Auto Start. Set Auto-Start Services to Disabled. Click Save.

From Ambari Web, browse to Admin > Service Auto Start. Set Auto-Start Services to Disabled. Click Save.

If you are running SmartSense in your cluster, stop the service.

From Ambari Web, browse to Services > SmartSense and select Stop from the Service Actions menu. Then, select Turn on Maintenance Mode from the Service Actions menu.

If you are running Ambari Metrics in your cluster, stop the service and put it in Maintenance Mode.

From Ambari Web, browse to Services > Ambari Metrics and select Stop from the Service Actions menu. Then, select Turn on Maintenance Mode from the Service Actions menu.

If you are running Log Search in your cluster, stop the service.

From Ambari Web, browse to Services > Log Search and select Stop from the Service Actions menu. Then, select Turn on Maintenance Mode from the Service Actions menu.

Stop the Ambari Server. On the host running Ambari Server:

ambari-server stop

Stop all Ambari Agents. On each host in your cluster running an Ambari Agent:

ambari-agent stop

Back up your existing Ambari Server database.

For example,to back up the default, embedded postgres db for Ambari:

 mkdir /root/backups/
pg_dump -U ambari ambari > /root/backups/ambari-before-upgrade.sql

The default password is: bigdata .

Upgrade your Ambari Server database to a current supported version, only if your Ambari Server database version is not supported on the target Ambari version.

To verify current supported versions, see the Hortonworks Support Matrix.

For example, if you are running postgres v9.4, you must upgrade postgres to v9.6 or v10.2. If you are running MariaDB 10.2, upgrading the Ambari Server database is not required.

Consult the documentation for your database type and version for specific database upgrade instructions.

Fetch the new Ambari repo and replace the old repository file with the new repository file on all hosts in your cluster.

	Important
	Check your current directory before you download the new repository file to make sure that there are no previous versions of the ambari.repo file. If you do not, and a previous version exists, the new download will be saved with a numeric extension, such as ambari.repo.1. Make sure that the version you copy is the new version.

Select the repository appropriate for your environment from the following list:

wget -nv https://archive.cloudera.com/p/ambari/2.x/2.7.4.0/centos7-ppc/ambari.repo -O /etc/yum.repos.d/ambari.repo

Upgrade Ambari Server. On the host running Ambari Server:

yum clean all

yum info ambari-server

In the info output, visually validate that there is an available version containing "2.7.4"

yum upgrade ambari-server

Check for upgrade success by noting progress during the Ambari Server installation process you started in Step 8.

	Important
	Confirm there is only one ambari-server*.jar file in /usr/lib/ambari-server. If there is more than one JAR file with name ambari-server*.jar, move all JARs except ambari-server-2.7.4*.jar to /tmp before proceeding with upgrade.

Upgrade all Ambari Agents. On each host in your cluster running an Ambari Agent:

yum upgrade ambari-agent

After the upgrade process completes, check each host to make sure the new files have been installed:

rpm -qa | grep ambari-agent

	Important
	If you have an HDF mpack installed, please use the specific instructions to Upgrade the HDF pack, before upgrading the Ambari-Server database schema.

Upgrade Ambari Server database schema. On the host running Ambari Server:

ambari-server upgrade

When the Ambari Server database schema has been upgraded, you should see command output like this:

Ambari Server ‘upgrade’ completed successfully

Start the Ambari Server. On the host running Ambari Server:

ambari-server start

Start all Ambari Agents. On each host in your cluster running an Ambari Agent:

ambari-agent start

Open Ambari Web.

Point your browser to the Ambari Web UI:

where <your.ambari.server> is the name of your ambari server host. For example, c7401.ambari.apache.org.

	Important
	Refresh your browser so that it loads the new version of the Ambari Web code. If you have problems, clear your browser cache manually, then restart Ambari Server.

Log in, using the Ambari administrator credentials that you have set up.

For example, the default name/password is admin/admin.

You will see a Restart indicator next to each service after upgrading. Ambari upgrade has added to/adjusted the configuration properties of your cluster based on new configuration types and properties being made available for each service with this release of Ambari. Review these changes by comparing the previous configuration with the latest version created by "ambari-upgrade".

	Important
	DO NOT RESTART these services unless future steps in the upgrade guide prompt you to do so. Manually restarting these services may significantly disrupt your upgrade. Ambari will restart each service automatically during the HDP upgrade.

If you have configured Ambari to authenticate against an external LDAP or Active Directory, you must re-run

ambari-server setup-ldap

If you have configured your cluster for Hive, Ranger or Oozie with an external database (Oracle, MySQL or PostgreSQL), you must re-run

ambari-server setup --jdbc-db and --jdbc-driver

to get the JDBC driver jar file in place.