Configuring impact analysis rules

This product ships with a set of default impact analysis rules that the impact assessment engine uses to identify potential impacts of a Change. You can modify these default rules, delete them, or create your own impact analysis rules to meet your impact analysis needs.

About this task

To configure the impact analysis rules, you must have a good understanding of the product data structure, CI relationship types, and the semantic meaning behind these relationships. It is recommended that you start by using the sample rules that are provided with the product, and begin configuring your own rules after you are familiar with the operation of the impact analysis engine and the overall impact analysis process.

Overview of impact analysis rules
The configuration management database (CMDB) captures relationships between configuration items (CIs). For example, an application RUNSON an application server. In each CI relationship, one CI is the source of the relationship, and the other CI is the target. In the example, the application CI is the source; the server is the target. Rules used by the impact analysis engine are based on these CI relationships and impact directions.
Default rules
Sample impact analysis rules are installed with IBM® Control Desk. These default rules can help you easily identify a substantial percentage of the impacts that will result from a change. Then, after you are familiar with the process, you can modify the default rules and create new rules.
Impact analysis system properties
You can use system properties to manage IBM Control Desk impact analysis.
Performance considerations for impact analysis
To get the best performance possible for impact analysis calculations, review the configuration options and configure system properties and rules to maximize performance for your environment.
Creating and modifying impact analysis rules
You can modify or delete the sample rules that are provided with this product and add new rules to match the needs of your data center. You can also construct new rules to mirror your configuration item (CI) classifications, the CI hierarchy, and other aspects of your CI configuration in the CMDB. The impact analysis engine uses the rules to traverse the CMDB and calculate impacts.
Testing rules
You can test impact analysis rules when you are creating or modifying a rule and want to make sure that the rule works as intended. For example, you might have run the impact analysis engine, and it did not identify a known impact that is based on your CMDB settings. You can create a rule to ensure that the impact is identified, or modify the rule that is used for this relationship. Testing the rule ensures that the impact is correctly identified.
Configuring the scope of impact analysis
When the impact analysis engine examines CI relationships to calculate impacts, it searches a specified number of levels away from the CI where it began the search. The engine finds impacts by examining related CIs for impacts, then examining CIs that are related to those CIs, and so on. A system property determines how many levels of related CIs the engine will examine to calculate impacts.
Configuring multi-thread impact analysis
The IBM Control Desk impact analysis engine uses a multi-threaded design and can analyze several different CI relationships at the same time. Administrators can configure the pmcom.TraversalMaxThreads system property to specify the maximum number of threads to process at one time.