What is Mission Critical?

So what is ‘Mission Critical’? The term gets used a lot and, frequently, confused. Here’s a clarification for the perplexed.

Mission Critical is describes something that your mission cannot succeed without. For example if you’re flying a plane your engines are mission critical. If you have an website that generates all your company revenue it’s mission critical.

Often mission critical is confused with two other terms; safety critical and high-availability. ‘Safety critical’ describes a system that, if it failed, would put lives at risk. Your car’s brakes, air-traffic control and are examples of safety critical systems.

High availability is used to denote systems that meet a designated level of operating continuity. For example your telephone system appears to run at all hours, day and night; also described as 24×7. In fact our telecommunications system has a high-availability of, at worst 99.999% uptime, equivalent to approximately five minutes of downtime per year. Many of the systems we use today have become high-availability systems, like ATMs, cable TV and web-sites. In general many businesses maintain some presence 24×7.

Although mission critical and high-availability systems can be useful, building them can incur extra costs. A wise step in creating any system is to identify only those components that are require to e mission critical and, possibly, high-availability.

They key to successful mission critical operations is understanding what your mission is; these questions can help:

What’s your mission?
What systems support your mission?
Which support systems are high-availability systems?

Take a look at your own software project and see how it measures-up against these questions.