Question 5132 – UGC NET CS 2018 JUNE Paper-2

Software availability:​ It is a software used to ensure that systems are running and available most of the time. High availability is a high percentage of time that the system is functioning. It can be formally defined as (1 – (down time/ total time))*100%. Although the minimum required availability varies by task, systems typically attempt to achieve 99.999% (5-nines) availability. This characteristic is weaker than fault tolerance, which typically seeks to provide 100% availability, albeit with significant price and performance penalties.
Given data,
-Software crashed 20 times in the year 2017
-each crash=2 minutes to restart.
-Software availability=?
1 year=365 days = 365*1440 minutes =525600 minutes.
→ Crash time =20*2
=40 minutes
→ Software availability = (525600-40) / 525600
= 0.999924
= (0.999924 * 100)
= 99.9924 %