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HDPCA Exam Objective – Change the configuration of a service using Ambari

by admin

Note: This is post is part of the HDPCA exam objective series

When you install an HDP cluster using ambari, it selects an optimum value of the configuration parameter for each of the services in the cluster. But you may have a requirement to change these default values. You can use ambari to change these settings pretty easily.

Viewing the current Service Config Properties

To view the config properties of a particular service (HDFS for example), goto Services > HDFS > Configs.

view current service config properties in ambari HDPCA

You would find the Basic and Advanced config properties here.

basic and advanced settings service config properties in ambari HDPCA

Changing Service Config Properties

In addition to modifying a large number of properties, making changes to a property often requires restarting daemons (and dependent daemons) across the entire cluster. Ambari makes this process easy for us.

For the example in this post, let’s change a Config property for HDFS service. We will change the
dfs.heartbeat.interval
from 3 seconds to 4 seconds. This determines the datanode heartbeat interval in seconds.

Change the configuration of a service in ambari

When the property is changed the “save” button becomes activated. A save/notes window will then be displayed. It is highly recommended that historical notes concerning the change be added to this window. For example, I have added the description of the change I made.

save configuration with description in ambari

save configuration changes successful in ambari HDPCA

Once the new property is changed, an orange Restart button will appear at the top left of the window. The new property will not take effect until the required services are restarted. The Restart button provides two options: Restart All and Restart DataNodes. To be safe, the Restart All should be used.

restart services after config property change HDPCA exam

Note: Restart All does not mean all the Hadoop services will be restarted; rather, only those that use the new property will be restarted.

We will use the Restart All option to restart all the affected service. Please confirm the restart on the pop-up window.

restart all affected service after config property change

service restart confirmation in ambari

You can view the progress is the progress window pop-up.

service restart progress ambari

Config Versioning

Ambari keeps track of all the changes made to the Service Config Properties. Every time you change any config property a new Version is created. You can revert back to a previous version anytime. Reverting back to a previous version also creates a new version.

view config property versions in ambari

As you can see in the above screenshot, we have the V4 version with the comment we provided while changing the Config Property.

Reverting back to a pervious version config

You can revert back to an older config by hovering over the version name. As shown in the example below, we have 2 options:
1. Compare config versions.
2. Make older config as current config.

view old config versions ambari HDP

Let’s make V3 as the current config to revert back the changes we did earlier in this post. Use the button “Make V3 current” to revert back to version “V3”. Provide an appropriate description for this change in the next pop-up window.

compare 2 config versions in ambari

description for the reverting back config version in ambari

Similar to changing the service config properties, we have to take the restart of all the affected service components here as well.

service restart after reverting config version in ambari

You can monitor the service restart progress in the pop-up window and can also view the logs if individual services.

monitor progress of restarting service in ambari HDPCA

Filed Under: Hadoop, HDPCA, Hortonworks HDP

Some more articles you might also be interested in …

  1. HDPCA Exam Objective – Configure HDFS ACLs
  2. HDPCA Exam Objective – Install and configure Knox
  3. CCA 131 – Perform OS-level configuration for Hadoop installation
  4. HDPCA Exam Objective – Configure a local HDP repository
  5. CCA 131 – Add a service using Cloudera Manager
  6. Converting Many Small Files To A Sequence File In HDFS
  7. HDPCA Exam Objective – Configure HiveServer2 HA ( Part 1 – Installing HiveServer )
  8. HDPCA Exam Objective – Restart an HDP service
  9. How to Configure Hive Authorization Using Apache Ranger
  10. CCA 131 – Install CDH using Cloudera Manager

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