Sometimes, organizations wish to merge, but their systems are so incompatible that it doesn't make sense to consolidate them. They allow both companies to continue to function with their existing systems, and they identify a third "long-term destination system" that everyone will ultimately be on.
If new organizations come on board and don't have a previous history established with the unworkable systems, they are often placed on the final target system from the start.
The work IT performs in mergers is so mission-critical that if it's determined that systems can't be readily consolidated and made to work together, the merger might be called off.
Needless to say, performing IT work for a merger is risky — not only technically but politically.
The practice developed in response to the problem of server sprawl, a situation in which multiple, under-utilized servers take up more space and consume more resources than can be justified by their workload. Of 518 respondents in a Gartner Group research study, six percent had conducted a server consolidation project, 61% were currently conducting one, and 28% were planning to do so in the immediate future.