Reduce Functions

Highest Severity

Uses the value of the highest severity; ignores weight.

Threshold

Uses the highest severity found more often than the given threshold. Value should be a percentage as a decimal so that .26 means 26%. This means at least 2 of 4 alarms need to be raised to change the business service.

Highest Severity Above

Uses the highest severity greater than the given threshold severity.

Exponential Propagation

This reduce function computes the sum of the given child severities based on a base number. For this computation, the severities are mapped to numbers:
\$WARNING=0, MINOR=1, MAJOR=2, CRITICAL=3\$

All other severities are ignored.

The aggregation uses the following formula to compute the resulting business service severity from its n child entities based on the base number b:
\$severity = |__log_{b}( sum_(i=1)^n b^(ch\ildSeverity_{i}) )__|\$

In summary, the base value defines how many items of a severity x will result in a severity x+1. Results lower than 0 are treated as NORMAL and results higher than 3 are treated as CRITICAL. If all input values are of severity INDETERMINATE, the result is INDETERMINATE.

For example, if the business service depends on four child entities with the severities WARNING, WARNING, NORMAL, and NORMAL and the base defined by the number 2, the following computation will be made:
\$severity = |__log_{2}( 2^{0} + 2^{0} + 0 + 0 )__| = |__log_{2}( 1 + 1 + 0 + 0)__| = |__log_{2}( 2 )__| = |__1__| = 1\$

which corresponds to the severity MINOR. The same computation with the base value of 3 results in:
\$severity = |__log_{3}( 3^{0} + 3^{0} + 0 + 0 )__| = |__log_{3}( 1 + 1 + 0 + 0)__| = |__log_{3}( 2 )__| = |__0.63__| = 0\$

which means WARNING.

Web-ICMP-1

1

0.2

Critical

Critical

0.2

0.2

0.2

0.2

0.2

Web-ICMP-2

1

0.2

Normal

Normal

0

0

0

0

0.2

Web-ICMP-3

3

0.6

Warning

Warning

0

0

0

0.6

0.6

Total

1.0

0.2

0.2

0.2

0.8

1

Percentage

100%

20%

20%

20%

80%

100%