The process of demand management is necessary for two main reasons:
• The arrival rate of work, such as transactions sent to a server, print jobs sent to a printer or calls to a service desk, is not steady. In other words, there are peaks and troughs over the hour and day, as well as seasonal increases or decreases in demand. There is rarely sufficient flexibility in IT resources to provide just enough capacity to meet the demand at each and every point in time.
• Fluctuations in demand and the challenge of providing just the right amount of capacity are sources of risk that the service provider should minimise. The decision on how much risk is acceptable is taken by the business, which may accept a level of spare capacity (and therefore extra cost) to reduce the risk.