Scott and McGuckin urged attendees to outline three to five tiers of IT service criticality -- in other words, choosing which applications need the most reliable and fastest IT services and which need something less.

"Not every application needs the same kind of processor or the same kind of facilities," McGuckin said. "We routinely see folks who have built out a highly redundant and expensive infrastructure, and many of the applications running in that data center don't need that level of uptime and redundancy. So that's wasted money. You want to match level of redundancy and uptime to needs of an application."

It's important to know what each application can tolerate, given that organizations are faced with deciding whether to site data centers in America, China or Europe. Companies that want to go overseas to reduce costs may be forced to stay local because of performance requirements.

"The speed of light is not our friend when it comes to figuring out how to provide the maximum uptime," McGuckin said.

An enterprise's data center plan should define the facilities that host IT services and the strategy for placing those services, taking into account the importance of each application and plans for responding to outages, data corruption and other problems, Gartner says. For global corporations, the strategy should also take into account the different laws in each country regarding intellectual property, privacy, security and labor.