Raw Network Availability
This metric calculates the number of network hours lost as a percentage of those available, per week.
Network hours available is calculated as the number of network ports mulitplied by time (weekly, hours).
Network availability is the actual number of network-hours delivered expressed as a percentage of those available.
A figure of 100% means that all ports were working for the whole week, (including weekends and evenings)
This metric provides a good overview of overall service availability. However, it can mask the impact of specific incidents, therefore a second metric, Network-Hours lost is also used.
Network User-Hours Lost.
This second metric attempts to convey the likely impact on working for any network service disruption. The metric is derived by multipliying the number of network ports affected by the duration of the outage. Although the value of lost hours can be high it should be considered that the total number of user-hours available in a given week is over 4.3 million so the metric should be read in this context. However it is useful to highlight the relative severity of any particular incident.
Week 1 represents the start of the calendar year 2008