WebSphere Virtual Enterprise (formerly Operations Optimization), Version 6.1
             Operating Systems: AIX, HP-UX, Linux, Solaris, Windows, z/OS


Configuring vertical stacking

You can configure vertical stacking to enable the application placement controller to start more than one instance of the dynamic cluster to improve bottleneck conditions within an application.

Before you begin

About this task

Use vertical stacking to improve bottleneck conditions in your application. With vertical stacking, multiple server instances can start on a node. By configuring multiple server instances, you can use all the power that is available on the nodes when a large workload exists for the application.

Procedure

  1. Determine whether your application has an internal bottleneck by profiling the application. The application placement controller assumes that the only resource bottleneck that an application might have is either in the processor or in memory. Otherwise, the application might have an internal bottleneck.
    1. Run an instance of the application on each node.
    2. Increase the load for the application.
    3. Using the runtime reports, the throughput curve and processor utilization on a node that is running the application. Click Runtime operations > Reports.
    If the throughput curve saturates while increasing the load, but the processor utilization remains well below 100%, the application might have an internal bottleneck. Configure vertical stacking to improve these bottleneck conditions. If the server instances are able to reach processor utilization near 100%, do not enable vertical stacking.
  2. Determine the appropriate stacking number. The stacking number is the number of application servers for a cluster that are needed to use all the power of a node. For more information about determining a stacking number, see Determining the stacking number for a dynamic cluster .
  3. Enable vertical stacking and the stacking number. If your dynamic cluster is deployed to a node group that has homogeneous nodes, you can configure the stacking number one time in the administrative console. If your dynamic cluster is deployed to a node group that has heterogeneous nodes, you must configure the stacking number by specifying custom properties.

Results

When a large workload exists, the application placement controller can fully use the power of the nodes by starting multiple cluster instances on each node.

The general formula to determine the percentage of the processor that is used by each instance on a node is 100%/maximum_number_of_stacked_instances. For example, if three instances are stacked, then workload is throttled to prevent any one of these instances from using more than 33% of the processor.

What to do next

Tune and monitor your application placement configuration.



Subtopics
Determining the stacking number for a dynamic cluster
Configuring a dynamic cluster with homogeneous nodes to support vertical stacking
Configuring a dynamic cluster with heterogeneous nodes to support vertical stacking
Related concepts
Dynamic clusters
Related tasks
Deploying enterprise applications
Creating dynamic clusters
Related reference
Static clusters versus dynamic clusters
Related information
Application placement custom properties
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Last updated: Oct 30, 2009 6:17:06 PM EDT
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