OVNPM 1.5.2 - Performance Agent for NonStop Display Agent Guide

Creating SystemInsight Metrics 153
14-3 Building a Metric Expression
After you select the metrics to combine, you must build a metric expression and designate a unit for each metric.
The value of a combined metric is the result of a particular operation on the values of its constituent metrics. A
metric expression indicates the operation to carry out on constituent metrics.
The following table explains the operators that you can use.
Operators Description
+, -, *, / Arithmetic Operators
Sum(), Max(), Min(), Ave(), Abs(), Raise to a PowerMathematical & Statistical Functions
<, <=, =, >=, > Comparative Operators
And, Or Logical Operators
Log, Exponent Scientific Functions
sin, cos, tan Trigonometric
() Value in Parenthesis
Steps to build a metric expression have been listed below.
1. From the Build New Metric dialog box, select an operator from the Expression list.
2. To select a metric, double click a metric from the Selected Metrics box, the letter that represents the metric
appears in the Expression box.
When necessary, replace the letter references in the metric expression (for example, A,B,C,...) by the
identification letters of the selected metrics. Delete any letter references unneeded from the metric
expression.
3. Enter a value in the Scale box. This is the default value for the metric when it is displayed in a view. The
value already in the box is the sum of the scales for all the individual metrics used.
NOTE: In a comparative expression, OVNPM substitutes zero if the result is false and one if it is true. Example,
if A > B is true, the value of the expression is 1
14-4 Designating Units in a Combined Metric
To complete the creation of a combined metric, you must designate either an actual or a generic unit for each of
its constituent metrics.
If you designate an actual unit, the metric is calculated only for that unit.
If you designate a generic unit, the actual unit is assigned at the time any view containing the metric is opened.
If you build a combined metric with generic unit references, you can designate the way in which actual units are
assigned at execution time. This enables you to avoid ambiguous assignments and assure that calculations are
performed correctly.
For example, assume that you are building a combined metric to compute an average of three individual, but
identical, metrics, Avg (A,B,C). You want to be sure that each of the individual metrics refers to a different unit.
Otherwise, your result is unreliable because there is no other way to assure that the same unit would not be used
more than once in the calculation.
In this example, the desired relative unit assignment is metric A[?1 unit], metric B[?2 unit], and metric C[?3 unit].
Because of this unit specification, OVNPM ensures that a different unit is assigned to each metric.
Creating SystemInsight Metrics