Conditional Aggregation

Aggregate metrics in eG Enterprise help administrators get a farm-wide view (rather than a server by server view of the target infrastructure). In the Adding/Modifying/Deleting Aggregate Tests topic, we described how mathematical functions like Avg, Sum, Min, Max, etc., can be used for computing the aggregate measure values for new aggregate tests. However, these aggregation functions can hide problem conditions. For instance, say you create an aggregate test to report the average CPU usage of a Windows server farm comprising of 4 Windows servers. If 3 out of the 4 servers register a CPU usage of 40% each, and one server registers 80%, then the average CPU usage for that farm will be 50%. This seemingly low aggregated CPU usage value does not reveal the fact that a single Windows server is seeing more than 80% of CPU resources.

To allow administrators greater flexibility and visibility into the health of the target infrastructure, eG Enterprise uses Conditional Aggregation. This is most useful when administrators only want to know the count or percentage of components that fulfill a defined condition or conditions. For instance, administrators may just want to know how many Windows servers are consuming over 80% of the CPU resources. Conditions are also useful when administrators want aggregate measures to report status values and not aggregated measure values; this will help the administrators determine how the fulfilment of a condition has impacted the health of the aggregate component. For example, an administrator may want the CPU usage measure to report the value Critical, if over 50% of the components in the aggregate are consuming over 80% of their individual CPU resources. The conditional aggregation capability helps in this case.

This conditional aggregation can be performed using a single condition or multiple conditions. Let us see how to perform both using separate illustrated examples.