Measuring availability is important to keep your application highly available. Only by measuring availability can you understand the performance of your application and examine how your application availability changes over time.
The most commonly used mechanism for measuring the availability of the application is calculating the percentage of the time and its accessibility for use by customers by using the following formula for a given period:
Application availability percentage = (total seconds in period - seconds system is down) / total seconds in period
For example, suppose that over the month of September, our workflow application was down twice, the first time it was down for 37 minutes and the second time it was down for 15 minutes.
Now, what was the availability of ADS workflow application?
Total number of seconds down = (37+15)*60 = 3120
Total number of seconds in month of September = 30 * 24 * 60 * 60 = 2592000
As per the above mentioned formula availability percentage = (2592000 - 3120) / 2592000 = 99.8795%
I will be happy to answer any of your questions.