Reduce Functions

Highest Severity

Uses the value of the highest severity, weight is ignored.

Threshold

Uses the highest severity found more often than the given threshold, e.g., 0.26 can also be seen as 26%, which means at least 2 of 4 alarms need to be raised to change the BS.

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.

For the aggregation the following formula will be used 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 as 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%