Capacity Management

Introduction and Objectives

The fundamental goal of Capacity Management is to make the available IT resources that customers, users and the IT department need to carry out their work efficiently, and to do so in a cost effective way.

This means Capacity Management has to:

• Stay up-to-date with the current state of the technology and expected future developments.
• Know about the company's business plans and service level agreements in order to forecast the necessary capacity.
• Analyse the performance of the infrastructure in order to monitor the use of existing capacity.
• Run capacity models and simulations for various possible future scenarios.
• Dimension services and applications appropriately, aligning them with business processes and the customer's real needs.
• Manage demand for computing services by rationalising their use.

Capacity Management aims to avoid situations in which unnecessary investments are made in technologies that do not meet the real needs of the business or which are over-dimensioned, or by contrast, to avoid situations in which productivity is undermined by a shortage of, or inefficient use of, the existing technology.

Both scenarios frequently arise and can often be found coexisting in a single organisation: managers, customers and computer personnel are blinded by technologies they do not really need and buy them while overlooking applications, hardware and services that would genuinely increase the productivity in their working environments.

One of the main tasks of Capacity Management is to qualify the perception that "capacity is cheap." Although, as a result of the falling cost of computer hardware and applications the cost of increasing capacity may initially not be very great, administering and maintaining disproportionate infrastructure can be very expensive in the long term.

The main benefits of good Capacity Management are:

• The performance of IT resources is optimised.
• The necessary capacity is available when it is needed, avoiding a negative impact on quality of service.
• Unnecessary expenses caused by "last minute" purchases are avoided.
• Growth of the infrastructure is planned, allowing it to be matched to real business needs.
• The cost of maintenance and administration associated with obsolete or unnecessary hardware and applications are reduced.
• Possible incompatibilities and faults in the IT infrastructure are reduced.

In summary: the management of purchases and maintenance of IT services is rationalised, with the consequent reduction in costs and increase in performance.

Implementing an appropriate Capacity Management policy can also run into serious difficulties, such as:

• Insufficient information for realistic capacity planning.
• Unrealistic expectations about the cost savings and improvements in performance.
• Inadequate resources to monitor performance properly.
• Distributed and excessively complex IT infrastructure making access to data difficult.
• There is insufficient commitment on the part of top management to implement the associated processes rigorously.
• Rapid technological change makes it necessary to continuously review the plans and scenarios envisaged.
• Correct dimensioning of Capacity Management itself: excessive zeal may result in expensive capacity analyses that might have been made unnecessary by buying new hardware or software.