Configuring elasticity mode

Configure elasticity mode to allow the application placement controller to minimize the number of used nodes remove nodes that are not needed. You configure elasticity mode while still meeting service policy goals. You can configure elasticity mode to allow the controller to add a node if the controller recognizes that a particular dynamic cluster is not meeting service policies even when all possible servers are in use.

1. Set the HAManagedItemPreferred_apc custom property to configure the application placement controller to start on a deployment manager or a node that will not be removed.

   Complete the following steps to configure the application placement controller to start on the deployment manager:

   1. In the administrative console, select System administration > Deployment manager > Java and process management > Process definition > Java virtual machine > Custom properties.
   2. Enter the name of the custom property as HAManagedItemPreferred_apc.
   3. Set the value of the custom property to true.
   4. Click Apply, and save your changes.
   5. Restart the current process in which the application placement controller is running.

   Complete the following steps to configure the application placement controller to start on the node:

   1. In the administrative console, select System administration > Nodes > node_name > node_agent_name > Java and process management > Process definition > Java virtual machine > Custom properties.
   2. Enter the name of the custom property as HAManagedItemPreferred_apc.
   3. Set the value of the custom property to true.
   4. Click Apply, and save your changes.
   5. Restart the current process in which the application placement controller is running.
2. Set the HAManagedItemPreferred_apc and HAManagedItemPreferred_cellagent custom properties to configure the controllers to start on the deployment managers of the center cell and the point cells when you enable elasticity mode in an environment in which multi-cell performance management is configured.

   Complete the following steps to configure the application placement controller to start on the deployment manager of the center cell:

   1. In the administrative console, select System administration > Deployment manager > Java and process management > Process definition > Java virtual machine > Custom properties.
   2. Enter the name of the custom property as HAManagedItemPreferred_apc.
   3. Set the value of the custom property to true.
   4. Click Apply, and save your changes.
   5. Restart the current process in which the application placement controller is running.

   Complete the following steps to configure the cell agent to start on the deployment managers of the point cells:

   1. In the administrative console, select System administration > Deployment manager > Java and process management > Process definition > Java virtual machine > Custom properties.
   2. Enter the name of the custom property as HAManagedItemPreferred_cellagent.
   3. Set the value of the custom property to true.
   4. Click Apply, and save your changes.
   5. Restart the current process in which the application placement controller is running.
3. Enable elasticity mode.
   Select Operational policies > Autonomic controllers > Application placement controller.
   1. Select the Enable elasticity operation check box.
   2. Set elasticity to either supervised or automatic mode.
   3. Set the timeout value.
      This value defines the allotted period of time that the application placement controller allows the task to complete. If the task does not complete within the specified amount of time, the application placement controller marks the task as failed. Specify the value in minutes. The default value is 10.

      Avoid trouble: If you change the elasticity operations timeout value in the WebSphere Application Server administrative console or by using a wsadmin command, make the same change in the pattern as well. When a new On-Demand Router (ODR) is requested by the Application Placement Controller (APC), the updated elasticity operations timeout value is not overwritten by the timeout value specified in the pattern.
   4. Click Apply, and save your changes.
4. Define the actions of the elasticity operations.
   An elasticity operation defines the runtime behaviors to monitor, and the corrective actions to take when the behaviors are present. Select Operational policies > Autonomic controllers > Application placement controller > Elasticity operation > operation..
   1. To add additional actions to the add operation, click Add Action....
      Select the custom action from the list of custom elasticity operation actions. If no custom actions are defined, selectOperational policies > Autonomic controllers > Application placement controller > Elasticity custom actions > New.
   2. To add additional actions to the remove operation, click Add action....
      Select the custom action from the list of custom elasticity operation actions. If no custom actions are defined, selectOperational policies > Autonomic controllers > Application placement controller > Elasticity custom actions > New.