Impacts priority
The impacts priority of a component reflects the urgency of resolving a problem based on the important CIs it impacts. To understand the concept of impacts priority, it is important to understand the concepts of "root cause CIs" and "important CIs."
Root cause CIs
CI A is said to be a root cause of CI B if the following criteria are met:
- A.status > OK
- A.status > A.impact_status
- No other CI exists in the "true impact path" from A to B.
A "true impact path" is a series of connected CIs by impact relationships so that each relationship is marked as "true impact." A true impact relationship is a relationship in which the propagated_status value is greater than or equal to the impact_status value of its consumer CI.
In other words, CI A is a root cause if its status is due to the events attached to it (or due to the manual status set by an operator) and if it ultimately participates in the determination of the computed status of an impacted CI B.
When a CI is a root cause, the events whose severity match the self status of that CI are considered "causal events."
Important CIs
In a service model, certain CIs represent vital parts of a business but are never directly impacted by events. They derive their status from other root cause CIs as shown in the following figure:
Propagation paths between root cause and important components 
To give more importance to root cause CIs impacting high-level CIs, the high-level CIs can be tagged as "priority propagators". Priority propagators CIs, also known as "important CIs," propagate their self priority back to their root cause CIs.
The various self_priority values propagated from the important CIs are consolidated in the root cause CIs by an impact priority formula. The output of this formula is stored in the raw_impact_priority slot of the root cause CI. It is a real value whose value belongs to the [sermod90:0,1] interval. This value is also set to the mc_smc_priority slot of the causal event. Sorting events by using this slot helps you to locate events that have maximum impact on your business.
The default impact priority formula called WEIGHTED is an internal function that combines various self priority values and gives more priority to root cause CIs impacting a lot of important CIs. The formula also takes into account the self_priority values of these CIs. The formula is as follows:
raw impact priority: rip = x/(x+1)
x = (SUM k=1..5 ( w[k] * ln(p[k] + 1) ) ) / ln(SUM k=1..5 (w[k]))
where
p[k] is the number of propagated self_priority with PRIORITY_k
and w[1] = 54, w[2] = 18, w[3] = 6, w[4] = 2, w[5] = 1
Alternatively, it is possible to use a simple formula that selects the highest propagated self_priority value and maps it to the [0,1] interval by modifying the PriorityFormula slot of the BMC_SERVICE_SCHEDULE_CONFIG data from WEGHTED to HIGHEST.
The impact_priority slot of a CI is the symbolic value corresponding to the raw_impact_priority value of this CI.
value in [0,.2[ corresponds to PRIORITY_5
value in [.2,.4[ corresponds to PRIORITY_4
This section assumes five priority levels as the default, but it is possible to change the number of priority levels by redefining the MC_PRIORITY enumeration.
The following figure summarizes the impact priority computation:
Impacts priority determination