Configure elasticity mode

Configure elasticity mode to allow the application placement controller to minimize the number of used nodes, and to remove nodes that are not needed, while still meeting service policy goals. Additionally, we can configure elasticity mode so that if the controller recognizes that a particular dynamic cluster is not meeting service policies although all possible servers are in use, the controller adds a node.

• For optimal performance, ensure that the dynamic clusters are running in supervised mode or automatic mode. It is not recommended to have elasticity mode enabled when the dynamic clusters are running in manual mode. However, if the dynamic clusters are running in manual mode with elasticity enabled, consider the following items:

  • The application placement controller does not add nodes to dynamic clusters in manual mode.

  • The application placement controller does not remove nodes from dynamic clusters in manual mode when a server is started on the specific nodes.

  • The application placement controller does remove nodes from dynamic clusters in manual mode when a server is not started on the specific nodes.

• It is not recommended to enable elasticity mode when the following option is set in the console for one or more dynamic clusters:

  If other dynamic clusters need resources, stop all instances of this cluster during periods of inactivity. If we have elasticity mode enabled and the option set, the application placement controller can remove all of the custom nodes in the cell.

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 console, select System administration > Deployment manager > Java and process management > Process definition > JVM > 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 the 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 console, select System administration > Nodes > node > node_agent_name > Java and process management > Process definition > JVM > 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 the 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 console, select System administration > Deployment manager > Java and process management > Process definition > JVM > 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 the 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 console, select System administration > Deployment manager > Java and process management > Process definition > JVM > 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 the 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 we change the elasticity operations timeout value in the WAS 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.gotcha

   4. Click Apply, and save the 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.

Subtopics

• (dist)(zos) Elasticity mode
  Use elasticity mode to add logic that causes the application placement controller to minimize the number of nodes used, as well as remove nodes that are not needed, while still meeting service policy goals. Additionally, we can use elasticity mode to add logic so that, when the controller recognizes that a particular dynamic cluster is not meeting service policies and has started all possible servers, the controller adds a node.

Related tasks

Configure multi-cell performance management: Star Topology

Create dynamic clusters

Intelligent Management: custom properties