In the beginning, IT ran on one platform - the mainframe. Workloads were predictable and stable, and we could schedule accordingly. But then came Unix, AS/400, Windows and a multitude of other platforms, all with accompanying workloads. The Internet and the need for 24x7 availability changed the workload model - "stable and predictable" flew out the window. Through all of this, the data center still has the same goal: manage the workloads to provide the highest level of service at the lowest cost.