When customers can not access Accounting Information Systems (AIS) applications, it is a big problem. Imagine customers being unable to buy merchandise from Amazon during the holidays. Imagine students being unable to register and pay for classes during registration time. These are examples of why firms require that their AIS applications retain high availability for use (greater than 99.9%), meaning that these systems will hardly ever suffer an outage.

Is this a fair demand for a firm and its customers to accept a much lower availability, such as 80%?