Securing investment in the capabilities required to run an always-on, always-available enterprise can be difficult, especially if you don't know your hourly cost of downtime. Because it is such a complex task, Forrester finds that the majority of companies have not calculated the cost of downtime for their critical services. Although trying to calculate the impact of an outage on reputation and customer retention can be a daunting task, just calculating revenue losses or productivity losses can be a worthwhile exercise.

Remember that not all outages are created equal: Timing and duration have a significant impact on the costs of downtime. In the original example, the outage was perfectly timed to impact the largest number of potential customers and thus have the largest business impact. What if this outage occurred at 3 a.m. ET instead of noon ET? Or what if it happened on a different day? Or, what if, instead of the Website being down for 4 hours straight on a single day, it was down for 30 minutes on eight different days? Shorter duration outages tend to be less disruptive than longer ones. All of this must be taken into account when calculating the impact of an outage.

Don't try and tackle the entire infrastructure all at once; break down your calculations on a service-by-service basis, starting with the most critical business services. Understanding the costs of downtime will guide the appropriate level of investment in downtime prevention for these services.

Many companies rigorously track server uptime and storage uptime, but few succeed in tracking a single service's uptime end to end, meaning from every infrastructure and software component that works together to deliver a single service. This, however, is the single most important thing that an IT department can track because it is the metric that gets closest to the actual customer experience. This is critical in "the age of the customer" where businesses compete and differentiate themselves on the experience of IT-enabled business processes and transactions more than ever.