A system having an MTTF of 80 hours with as standard deviati

A system having an MTTF of 80 hours with as standard deviation of 2 hours would probably be rated higher in reliability than a system having an MTTF of 80 hours and a standard deviation of 40 hours. Briefly explain why this would be true.

Solution

MTTF means the mean time to failure is 80hours ... i.e a failure may occur every 80 hours.
Knowing the MTTF and past failire timestamp companies can easily assess the approximate time period at which failure may occur hence make the mock servers or mirror servers active or available to service customer or consumer requests ,so that the business operations continue during the original server downtime period.The time period is calculated using standard deviation constant
i.e MTTF + / - S.D
If S.D is high the time period for which the mirror servers and its resources to be available becomes very high and hence double the operational costs for a large time period.Conversely if S.D is less ,then time period is less hence the operational costs are considerably very less than the previous case.

Hence for the given scenario low S.D is better than higher S.D.

Here 80 +/-40 implies about half of the time i.e 40 out of 80 hours of the day the original and mirror servers should be available .
Whereas 80 +/- 2 means only for very less time period i.e 4 hours for 80 hours both servers are to be available.