Adding a Host to the Cluster
You can add one or more hosts to your Hadoop cluster using the Add Hosts wizard, which will install the Oracle JDK, CDH, Impala (optional) and the Cloudera Manager Agent packages. After these packages are installed and the Cloudera Manager Agent is started, the Agent will connect to the Cloudera Manager Server and you will then be able to use the Cloudera Manager Admin Console to manage and monitor CDH on the new host.
The Add Hosts wizard does not create roles on the new host; once you have successfully added the host(s) you can either add roles, one service at a time, or apply a host template, which can define role configurations for multiple roles.
All hosts in a single cluster must be running the same version of CDH, for example CDH 4.7.
When you install the new hosts on your system, you must install the same version of CDH to enable the new host to work with the other hosts in the cluster. The installation wizard lets you select the version of CDH you want to install, and you can choose a custom repository to ensure that the version you install matches the version on your other hosts.
If you are managing multiple clusters, be sure to select the version of CDH that matches the version in use on the cluster where you plan to add the new hosts.
Using the Add Hosts Wizard to Add Hosts
You can use the Add Hosts wizard to install CDH, Impala, and the Cloudera Manager Agent on a host.
Step 1: Disable TLS Encryption or Authentication
If you have enabled TLS encryption or authentication for the Cloudera Manager Agents, you must disable both of them before starting the Add Hosts wizard. Otherwise, skip to the next step.
To disable TLS:
- From the Administration tab, select Settings.
- Select the Security category.
- Disable all levels of TLS that are currently enabled by deselecting the following options: Use TLS Encryption for Agents, and Use TLS Authentication of Agents to Server.
- Click Save Changes to save the settings.
- Restart the Cloudera Management Server to have these changes take effect.
Step 2: Using the Add Hosts wizard
To use the Add Hosts wizard:
- Click the Hosts tab.
- Click the Add Hosts button.
- Follow the instructions in the wizard to install the Oracle JDK, CDH, Impala, and Cloudera Manager Agent packages or parcels and start the Agent.
- In the Specify hosts for your CDH Cluster installation page, you can search for new hosts to add under the New Hosts tab. However, if you have hosts that are already known to Cloudera Manager but have no roles assigned, (for example, a host that was previously in your cluster but was then removed) these will appear under the Currently Managed Hosts tab.
- If you are installing on new hosts (not already managed) Cloudera Manager installs its
agent on those hosts. The Cloudera Manager agents must match exactly the version of
your installed Cloudera Manager server and existing agents.
- If your Cloudera Manager server was installed from Cloudera's website (http://archive.cloudera.com), you can select "Matched Repository" in the section of the wizard where you specify the Cloudera Manager version, and Cloudera Manager will install the agent that matches the version of your server. .
- If you installed Cloudera Manager from a customer repo (for example, a local repo you created), you must specify the path to the correct repo version in the "Customer Repo" field. You can find the older versions of Cloudera Manager by going to http://archive.cloudera.com/cm4/ and navigating to the repo for your Operating System. (You can find the version of Cloudera Manager you are running from the About command on the Support menu in the Cloudera Manager admin console.)
- If you did your initial CDH installation using parcels, Cloudera Manager automatically downloads those same parcels to the new hosts.
- You will have an opportunity to add (and start) role instances to your newly-added hosts using a Host Template.
- You can select an existing host template, or create a new one.
- To create a new host template, click the + Create... button. This will open the Create New Host Template pop-up. See Working with Host Templates for details on how you select the role groups that define the roles that should run on a host. When you have created the template, it will appear in the list of host templates from which you can choose.
- Select the host template you want to use.
- By default Cloudera Manager will automatically start the roles specified in the host template on your newly added hosts. To prevent this, uncheck the option to start the newly-created roles.
- When the wizard is finished, you can verify the Agent is connecting properly with the Cloudera Manager Server by clicking the Hosts tab and checking the health status for the new host. If the Health Status is Good and the value for the Last Heartbeat is recent, then the Agent is connecting properly with the Cloudera Manager Server.
Note that if you did not specify a Host template during the Add Hosts wizard, then no roles will be present on your new hosts until you add them. You can do this by adding individual roles under the Instances tab for a specific service, or by using a Host Template. See Adding Role Instances for information about adding roles for a specific service. See Working with Host Templates to create a host template that specifies a set of roles (from different services) that should run on a host.
Step 3: Enable TLS Encryption or Authentication After Using the Add Hosts Wizard
If you previously enabled TLS security on your cluster, you must re-enable the TLS options on the Administration page and also configure TLS on each new host after using the Add Hosts wizard. Otherwise, you can ignore this step.
Adding a Host by Installing the Packages Using Your Own Method
If you used a different mechanism to install the Oracle JDK, CDH, Cloudera Manager Agent packages, you can use that same mechanism to install the Oracle JDK, CDH, Cloudera Manager Agent packages and then start the Cloudera Manager Agent.
To add a host by installing the packages using your own method:
- Install the Oracle JDK, CDH, Cloudera Manager Agent packages using your own method. For instructions on installing these packages, see Installation Path B - Installation Using Your Own Method.
- After installation is complete, start the Cloudera Manager Agent. For instructions, see Starting the Cloudera Manager Agents.
- After the Agent is started, you can verify the Agent is connecting properly with the Cloudera Manager Server by clicking the Hosts tab and checking the health status for the new host. If the Health Status is Good and the value for the Last Heartbeat is recent, then the Agent is connecting properly with the Cloudera Manager Server.
- If you have enabled TLS security on your cluster, you must enable and configure TLS on each new host. Otherwise, ignore this step.
- Enable and configure TLS on each new host by specifying 1 for the use_tls property in the /etc/cloudera-scm-agent/config.ini configuration file.
- Configure the same level(s) of TLS security on the new hosts by following the instructions in Configuring TLS Security for Cloudera Manager.
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