Role Groups

Minimum Required Role: Configurator (also provided by Cluster Administrator, Full Administrator)

A role group is a set of configuration properties for a role type, as well as a list of role instances associated with that group. Cloudera Manager automatically creates a default role group named Role Type Default Group for each role type.Each role instance can be associated with only a single role group.

Role groups provide two types of properties: those that affect the configuration of the service itself and those that affect monitoring of the service, if applicable (the Monitoring subcategory). (Not all services have monitoring properties). For more information about monitoring properties see Configuring Monitoring Settings.

When you run the installation or upgrade wizard, Cloudera Manager configures the default role groups it adds, and adds any other required role groups for a given role type. For example, a DataNode role on the same host as the NameNode might require a different configuration than DataNode roles running on other hosts. Cloudera Manager creates a separate role group for the DataNode role running on the NameNode host and uses the default configuration for DataNode roles running on other hosts.

You can modify the settings of the default role group, or you can create new role groups and associate role instances to whichever role group is most appropriate. This simplifies the management of role configurations when one group of role instances may require different settings than another group of instances of the same role type—for example, due to differences in the hardware the roles run on. You modify the configuration for any of the service's role groups through the Configuration tab for the service. You can also override the settings inherited from a role group for a role instance.

If there are multiple role groups for a role type, you can move role instances from one group to another. When you move a role instance to a different group, it inherits the configuration settings for its new group.

Creating a Role Group

  1. Go to a service status page.
  2. Click the Instances or Configuration tab.
  3. Click Role Groups.
  4. Click Create new group....
  5. Provide a name for the group.
  6. Select the role type for the group. You can select role types that allow multiple instances and that exist for the service you have selected.
  7. In the Copy From field, select the source of the basic configuration information for the role group:
    • An existing role group of the appropriate type.
    • None.... The role group is set up with generic default values that are not the same as the values Cloudera Manager sets in the default role group, as Cloudera Manager specifically sets the appropriate configuration properties for the services and roles it installs. After you create the group you must edit the configuration to set missing properties (for example the TaskTracker Local Data Directory List property, which is not populated if you select None) and clear other validation warnings and errors.

Managing Role Groups

You can rename or delete existing role groups, and move roles of the same role type from one group to another.
  1. Go to a service status page.
  2. Click the Instances or Configuration tab.
  3. Click Role Groups.
  4. Click the group you want to manage. Role instances assigned to the role group are listed.
  5. Perform the appropriate procedure for the action:
    Action Procedure
    1. Click the role group name, click next to the name on the right and click Rename.
    2. Specify the new name and click Rename.
    Delete You cannot delete any of the default groups. The group must first be empty; if you want to delete a group you've created, you must move any role instances to a different role group.
    1. Click the role group name.
    2. Click next to the role group name on the right, select Delete, and confirm by clicking Delete. Deleting a role group removes it from host templates.
    1. Select the role instance(s) to move.
    2. Select Actions for Selected > Move To Different Role Group....
    3. In the pop-up that appears, select the target role group and click Move.