theGuard! ApplicationManager by default offers a reporting template specifically tailored to this problem.
The template shows the availability according to different criteria (up/down/not monitored) as calculated overall availability and as a graph.
The report can display the availability of all systems belonging to an overall system (SAP instances, DB instances, servers …).
This allows for an easy root cause analysis.
The availability of individual components in applications and systems (e.g. Oracle Tablespaces, Windows Services) can be traced as well.