For role types that allow multiple instances on multiple nodes, such as DataNodes, TaskTrackers, RegionServers (and many others), you can create multiple role groups to allow one set of role instances to use different configuration settings than another set of instances of the same role type.
If there are multiple role groups for a role type, you can move role instances from one group to another.
Creating a New Role Group
To create a new role group for a role type:
- Click the Services tab and select the service where you want to create a new role group.
- Pull down the Configuration tab at the top of the window and select Role Groups.
- Click Create New Group.
- Provide a name for the group.
- Select the type of role for the group. You will only be able to select role types that allow multiple instances, and that exist the Service you have selected.
- In the Copy From field, select the source of the basic configuration information for this role group; you can use any existing role group of the appropriate type, or you can choose None and the role group will be set up with all generic default values.
If you select None as the source, the default values are not the same as the values Cloudera Manager sets in the base role group, as Cloudera Manager specifically sets the appropriate configuration properties for the services and roles it installs. After you create your group using None 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 an Existing Role Group
For an existing role groups, you can rename or delete them, and move roles from one to another (of the same role type).
- Click the Services tab and select the service you want to manage.
- Pull down the Configuration tab at the top of the window and select Role Groups. The Role Groups panel shows the Role Groups you can manage. This will include any groups created automatically by Cloudera Manager (such as the Base group for each role type) as well as any groups of the appropriate role types that you have created.
- Click the group you want to manage.
If there are role instances assigned to this role group, they are listed here.
- To rename the role group, click the Rename button, then enter the new name in the pop-up window, and click Rename to complete the action. You cannot rename a base group.
- To delete the role group, click the Delete button, and confirm you want to perform the delete. You cannot delete any of the base groups, and you cannot delete a group if it has role instances associated with it. If you want to delete a group you've created, you must move any role instances to a different role group.
- To move a role to a different role group:
- Select the role instance(s) you want to move
- Pull down the Actions for Selected menu and select Move...
- In the pop-up that appears, select the group to which you want to move your selected role instance, and click Move.