Monitor and tuning the application placement controller

Operating Systems: AIX, HP-UX, Linux, Solaris, Windows, z/OS

Monitor and tuning the application placement controller

Application placement is designed to work with the default settings that are provided. However, there can be times when fine tuning the application placement controller becomes necessary to ensure the best results.

Before you begin
Before you can tune application placement, have dynamic application placement running. Follow the information in Configure dynamic application placement to enable application placement.
Depending on your administrative role, you are allowed specific privileges when configuring the autonomic managers. The following list shows the administrative roles and privileges for configuring the autonomic managers:
Monitor: Can view the information.
Operator: Can view the information on the configuration tab. Can change the settings on the runtime tab.
Configurator: Can change the configuration but not the runtime settings.
Administrator: Has all privileges.

About this task
Tune the application placement controller when your dynamic operations environment is not performing as expected.

Procedure

In the administrative console, click Operational policies > Autonomic controllers > Application placement controller.
Determine whether you want to modify the persistent settings in the configuration tab, or test runtime settings, which last for the life of the application placement controller. You can choose to modify the runtime settings and then find those settings are actually what you want to use as permanent settings. You can make runtime settings persistent settings by clicking Save to repository.
Modify the application placement controller settings, as needed.
The table following these steps contains the general configuration settings.
Define custom properties to change placement behavior.
You can specify the reservedMemoryFixed and reservedMemoryPercent custom properties to define how much node memory to reserve for processes that are not related to WebSphere^® Application Server or WebSphere Virtual Enterprise. For information about custom properties that you can set on the application placement controller, see Application placement custom properties.
Click Apply or OK. Save your changes.
Iterate and modify the settings as needed. Make changes until you discover the best possible configuration for your environment.

Results

Table 1. General configuration settings

Enable Enables or disables the application placement controller. If you disable the application placement controller, you are disabling all autonomic operations for the dynamic clusters. After the placement controller is disabled, no dynamic changes occur with regard to the size and placement of applications on the dynamic cluster. This action is equivalent to turning all dynamic clusters to static clusters.
Approval timeout Controls how long the runtime task sits in the queue awaiting action before it expires automatically. Acceptable time values are 1 to 60 minutes. This setting is particular to the supervised operating mode. When the operating environment is set to run in supervised mode, the application placement controller creates tasks, but must wait for approval from the system administrator before making changes.
The application placement controller treats runtime tasks that are timed out as user-rejected tasks.
Server operation timeout Represents the amount of time, in minutes, that the application placement controller waits for a start or stop operation to complete before the operation is considered a failure. If a server fails to start before the timeout, the server is put into maintenance mode. The application placement controller avoids trying to start that server again until you manually fix the start issue and manually start the server. When the server starts, the application placement controller detects that the server has started.
Set this value to the predicted worst case time to start or stop a server. Acceptable values are between 1 to 60 minutes.
Minimum time between placement change Specifies the amount of time that the application placement controller waits before initiating a new batch of changes. The application placement controller might wait for a batch of changes after completing previous changes, or encountering a timeout. Acceptable values can range from 1 minute to 24 hours.
When setting this value, consider the overhead that is associated with starting and stopping servers. Starting or stopping servers can take several minutes and might introduce an additional load to the nodes.
If you allow the placement controllers to readjust application placement too often, the added overhead negates the increased performance gains that can be earned by readjusting the size of dynamic clusters. For example, if a server takes one minute to start, and the setting for the minimum time between placement changes is 20 minutes, then placement changes have a performance impact of approximately 5%.
Set this value at least 20 to 30 times larger than the time necessary to start a server. A value greater than several hours prevents application placement changes from happening more than once a day. If you believe that traffic load and application demands adjust several times during a day, you might want to allow placement changes to occur more frequently.

The application placement controller is tuned for its best performance.

Related concepts

Overview of application placement

Related tasks

Configure dynamic application placement

Related reference

Administrative roles and privileges
PlacementControllerProcs.jacl script

Enable	Enables or disables the application placement controller. If you disable the application placement controller, you are disabling all autonomic operations for the dynamic clusters. After the placement controller is disabled, no dynamic changes occur with regard to the size and placement of applications on the dynamic cluster. This action is equivalent to turning all dynamic clusters to static clusters.
Approval timeout	Controls how long the runtime task sits in the queue awaiting action before it expires automatically. Acceptable time values are 1 to 60 minutes. This setting is particular to the supervised operating mode. When the operating environment is set to run in supervised mode, the application placement controller creates tasks, but must wait for approval from the system administrator before making changes. The application placement controller treats runtime tasks that are timed out as user-rejected tasks.
Server operation timeout	Represents the amount of time, in minutes, that the application placement controller waits for a start or stop operation to complete before the operation is considered a failure. If a server fails to start before the timeout, the server is put into maintenance mode. The application placement controller avoids trying to start that server again until you manually fix the start issue and manually start the server. When the server starts, the application placement controller detects that the server has started. Set this value to the predicted worst case time to start or stop a server. Acceptable values are between 1 to 60 minutes.
Minimum time between placement change	Specifies the amount of time that the application placement controller waits before initiating a new batch of changes. The application placement controller might wait for a batch of changes after completing previous changes, or encountering a timeout. Acceptable values can range from 1 minute to 24 hours. When setting this value, consider the overhead that is associated with starting and stopping servers. Starting or stopping servers can take several minutes and might introduce an additional load to the nodes. If you allow the placement controllers to readjust application placement too often, the added overhead negates the increased performance gains that can be earned by readjusting the size of dynamic clusters. For example, if a server takes one minute to start, and the setting for the minimum time between placement changes is 20 minutes, then placement changes have a performance impact of approximately 5%. Set this value at least 20 to 30 times larger than the time necessary to start a server. A value greater than several hours prevents application placement changes from happening more than once a day. If you believe that traffic load and application demands adjust several times during a day, you might want to allow placement changes to occur more frequently.