Total Downtime Calculations
The total downtime of the system in a specified time interval can be calculated. In the following formula for total downtime, the start time of the computation is used as the starting point of the interval.
Where:
TDT(t1, t2) = The total downtime of the system in the time interval t1 and t2.
A(t) = The availability of the system at time t.
U(t) = The unavailability of the system at time t.
t1 and t2 = The starting and ending points of the time interval.
Numerical methods are used to compute this integral.
From the total downtime equation, we can easily find the relationship between total downtime and mean availability: