mean down time (MDT)

Mean Down Time(MDT) means the average duration of a fault. It is a measure of the availability of systems, networks and services.

Mean down time refers to the average time required to eliminate a fault after the failure of a system, device or service. During the mean down time, the technical equipment is not operational. Mean fault duration includes repair, maintenance, and setup times and all administrative delays.

The difference between the mean fault duration and the mean repair time, the Mean Time to Repair( MTTR), is that the mean fault duration concerns all repair and other delays until operations are restored, whereas the MTTR concerns only the time required for repair.