Availability

The general formula for availability is:

Availability = [MTBF/(MTBF+MTTR)] x 100

Availability is a function of the total service time, the mean time between failure (MTBF), and the mean time to repair (MTTR).

### Details

Unit: Percentage

Direction: Maximize

### Benchmark Results

This KPI is most used for:
Operational Excellence

1. Can you use this general formula also for hardware? Thanks on advance

2. Dears

please advice regarding the availability of the whole system ; i think the above availability is for a one service/link/node, so in case we have number of nodes occupied by number of links each link occupied by number of service how can i calculate the system availability.

thanks for your swift feed back.

Tarig Alamin

3. There are two more formulas for Service Availability, this one here relates only to a single instance of a productive unit.

In Serial Mode:

that is one Productive Unit (PU) after another PU the formula is:

Service Availability = PU1 availability * PU2 availability (* PUn availability and so on)

so 100% * 98% = 98%
and 98% * 98% = 96.04% availability

In Parallel mode:

where PU1 and PU2 are linked such that one takes over should the other fail the PU Total availability needs to be calculated first:

1 – (1-PU1 availability(original availabilty measure for single PU)))*(1-PU2 availabilty))

so (PU1 and 2 are parallel such that PU2 takes over if PU1 fails) 1-((1-98%(PU1))*(1-98%(PU2)))=99.96%

it is possible now to combine the serial and parallel availability calculations to create very complex Service Availabilities.

I always draw out a diagram of how to work this out, makes life a lot easier.

regards
Sean