WebSphere Extended Deployment implements a Tivoli Intelligent Orchestrator objective analyzer that is specialized for the WebSphere Extended Deployment domain. The objective analyzer enables autonomic or semi-autonomic provisioning based on performance goals. The objective analyzer is included in the software driver and plugs into Tivoli Intelligent Orchestrator during the WebSphere Extended Deployment driver installation. When Tivoli Intelligent Orchestrator decides that the WebSphere Extended Deployment node cluster group needs additional servers, Tivoli Intelligent Orchestrator provides more servers to that cluster to balance the resource load.
Probability of breach
The function of objective analyzers is to help Tivoli Intelligent Orchestrator to make better provisioning decisions for a particular cluster of machines. For example, each objective analyzer is assigned to a cluster. Tivoli Intelligent Orchestrator calls each active objective analyzer whenever Tivoli Intelligent Orchestrator needs to make a provisioning decision. In the current version of Tivoli Intelligent Orchestrator, provisioning decisions occur approximately every thirty seconds. The objective analyzer tells Tivoli Intelligent Orchestrator how likely the assigned cluster is to fail to meet its performance goals for a given quantity of machines. The likelihood that a cluster fails to meet performance goals is called probability of breach. By repeatedly calling all the currently assigned objective analyzers with different numbers of machines, Tivoli Intelligent Orchestrator can determine the best course of action for this cycle.
The WebSphere Extended Deployment objective analyzer communicates with WebSphere Extended Deployment to determine how busy WebSphere Extended Deployment currently is, and how many additional resources can be useful. Coupled with Tivoli Intelligent Orchestrator knowledge of how many machines are currently assigned to the cluster, the WebSphere Extended Deployment objective analyzer can respond to Tivoli Intelligent Orchestrator questions. Tivoli Intelligent Orchestrator takes the responses from the WebSphere Extended Deployment objective analyzer, combines them with responses from other objective analyzers that are working for other clusters, and determines the optimal machine allocation at this time.
The objective analyzer does not make specific recommendations if the number of machines allocated to the cluster in question changed within the last 15 minutes. A busy WebSphere Extended Deployment system takes time to stabilize after the node count changes, so the WebSphere Extended Deployment objective analyzer does not make allocation recommendations during the stabilization period.
If you are using the objective analyzer, you must have at least one server in each application tier. To prevent the server count from going below 1, adjust the Servers minimum and Servers Maximum fields on the Application Tier Configuration panel. Set the minimum field to at least 1. If you are not using the objective analyzer and are using Tivoli Intelligent Orchestrator in manual mode or in some other way, you do not need to configure one server in each application tier.