Using composite parameters
The PATROL for Linux provides the ability to create an aggregate parameter. This aggregate parameter consists of two or more existing parameters. BMC PATROL evaluates the values of these designated parameters and then determines, based on user-defined criteria, whether the cumulative effect of these parameters' states warrants a warning or an alarm.
Composite parameters give you the ability to create parameters whose values are dependent on one or more existing PATROL parameters. You can then use PATROL alarm settings and recovery actions on the newly created parameters in the same way that you use alarm settings and recovery actions on other parameters. For example, you can create a composite parameter that triggers an alarm when paging activity is high while processor utilization is low.
A composite parameter consists of a user-defined Boolean expression and a result.
- The Boolean expression can consist of
- existing PATROL parameters
- constant values
- relationship operators, < (less than), > (greater than), == (equal to)
- Boolean operators, && (and), || (or), ! (not))
- string operators
For more information about the relationship operators and the Boolean operators, see the PSL Reference Manual.
- The result is a PATROL parameter condition, such as alarm when true, or warn when false. For example, you can build a composite parameter that triggers a PATROL alarm indicating a low memory condition when both of the following conditions are true:
See Examples for more information.
Introduction to using composite parameters
Composite parameters are parameters whose values are dependent on one or more existing BMC PATROL parameters. You can assign BMC PATROL alarm settings and recovery actions on the newly created parameters in the same way that you use alarm settings and recovery actions on other parameters.
A composite parameter expression consists of one or more relational clauses joined by Boolean (logical) operators. A relational clause can have one of the following forms:
- Parameter (relational operator) constant or string
- Constant or string (relational operator) parameter
- Parameter (relational operator) parameter
A relational operator can be any of the standard PSL relational operators (that is, <, >, ==, <=, >=).
Relational clauses can be combined using the logical operators AND (&&) and OR (||).
The result of a composite parameter expression is a BMC PATROL parameter condition, such as "alarm when true," or "warn when false."
For example, you can build a composite parameter that triggers a BMC PATROL alarm indicating low memory conditions only when both of the following conditions is true:
- IOWaitTime > 40
See Examples-of-COMPOSITES-parameter-expressions for detailed examples.
Working with Composite Parameter Expressions
You can enter composite parameter expressions manually or by using the expression entry wizard. Even if you use the expression entry wizard, you might need to edit the expression manually for complex expressions.
You can create, edit, and delete composite parameter expressions using NUK_COMPOSITES_COLLECTOR with the application icon shown in the following figure.
NUK_COMPOSITES_COLLECTOR Application Icon 
After you create a composite parameter, the icon for the composite parameter appears in the COMPOSITES container (see the following figure) after the next scheduled update of the parameter.
NUK_COMPOSITES Parameters Container Icon 
The following topics are discussed in this section:
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