6.1  Introduction

6.1.1 Why Capacity Management?
6.1.2 Goal for Capacity Management
6.1.3 Scope of Capacity Management

Capacity Management is responsible for ensuring that the Capacity of the IT Infrastructure matches the evolving demands of the business in the most cost-effective and timely manner. The process encompasses:

• the monitoring of performance and throughput of IT Services and the supporting Infrastructure components
• undertaking tuning activities to make the most efficient use of existing resources
• understanding the demands currently being made for IT resources and producing forecasts for future requirements
• influencing the demand for resource, perhaps in conjunction with Financial Management
• the production of a Capacity Plan which enables the IT Service provider to provide services of the quality defined in Service Level Agreements (SLAs).

As shown in Figure 6.1, Capacity Management is essentially a balancing act; balancing:

• cost against Capacity - i.e. the need to ensure that processing Capacity that is purchased is not only cost justifiable in terms of business need, but also the need to make the most efficient use of those resources, and
• supply against demand - i.e. making sure that the available supply of processing power matches the demands made on it by the business, both now and in the future; it may also be necessary to manage or influence the demand for a particular resource.

Figure 6.1 - Capacity Management - a balancing act

This Chapter provides guidance on:

• how to justify and establish a Capacity Management process
• the activities and tasks that need to be undertaken
• planning and implementing Capacity Management in an IT organisation
• the responsibilities of the Capacity Management process

6.1.1  Why Capacity Management?

Capacity Management is often viewed as on old-fashioned, mainframe-oriented discipline. IT Services Managers in charge of distributed computing facilities have argued that Capacity Management takes more time and effort, and therefore cost, than it is worth, and that it would be better to 'pay for upgrades as required'. IT organisations with this view tend to exhibit the following symptoms:

• procurement of IT equipment is justified on an individual capital return basis, rather than the overall corporate requirement
• there are no corporate Capacity Plans
• no business Capacity forecasts are produced
• network Capacity Management is done reactively
• Capacity Management of servers is also done reactively, albeit less often
• little or no Capacity Management is performed on desktop equipment.

This insular, short-term attitude is the very antithesis of Capacity Management.

Managing the Capacity of large networks of distributed equipment is more complex than in the 'good old days' of the mainframe, and for all thriving organisations the financial investment in IT is increasing. Therefore it makes even more sense to plan for growth. While the cost of the upgrade to an individual component in a distributed environment is usually less than the upgrade to a component in a mainframe environment, there are often many more components in the distributed environment that need to be upgraded. Also there could now be economies of scale, because the cost per individual component could be reduced when many components need to be purchased. So Capacity Management should have input to the procurement process to ensure that the best deals with suppliers are negotiated.

A corporate Capacity Management process ensures that the entire organisation's Capacity requirements are catered for. The cost of upgrading all the desktop equipment in an organisation could easily exceed the cost of a mainframe upgrade. Capacity Management should have responsibility for the 'refresh policy', ensuring that desktop equipment has sufficient Capacity to run the applications that the business requires for the foreseeable future.

Capacity Management provides the necessary information on current and planned resource utilisation of individual components to enable organisations to decide, with confidence:

• which components to upgrade (i.e. more memory, faster storage devices, faster processors, greater bandwidth)
• when to upgrade - ideally this is not too early, resulting in expensive over-Capacity, nor too late, resulting in bottle-necks, inconsistent performance and ultimately Customer dissatisfaction and lost business opportunities
• how much the upgrade will cost - the forecasting and planning elements of Capacity Management feed into budgetary lifecycles, ensuring planned investment.

Many of the other Service Management processes are less effective if there is no input to them from the Capacity Management process. For example:

• can the Change Management process properly assess the effect of any Change on the available Capacity?
• when a new service is implemented, can the Service Level Management (SLM) process be assured that the Service Level Requirements (SLRs) of the service are achievable, and that the SLAs of existing services will not be impacted?
• can the Problem Management process properly diagnose the underlying cause of Incidents caused by poor performance?
• can the Service Continuity process accurately determine the Capacity requirements of the key business processes?

Capacity Management is one of the forward-looking processes, which, when properly carried out, can forecast business impacts before they happen.

6.1.2  Goal for Capacity Management

Capacity Management needs to understand the business requirements (the required Service Delivery), the organisation's operation (the current Service Delivery) and the IT Infrastructure (the means of Service Delivery), and ensure that all the current and future Capacity and performance aspects of the business requirements are provided cost-effectively.

However Capacity Management is also about understanding the potential for Service Delivery. New technology needs to be understood and, if appropriate, used to deliver the services required by the business. Capacity Management needs to recognise that the rate of technological change will probably increase and that new technology should be harnessed to ensure that the IT Services continue to satisfy changing business expectations.

While these two laws hold true then effective Capacity Management is even more important as supply and demand grow exponentially.

Goal Statement

The Capacity Management process's goal is 'to ensure that cost justifiable IT Capacity always exists and that it is matched to the current and future identified needs of the business'.

6.1.3  Scope of Capacity Management

The Capacity Management process should be the focal point for all IT performance and Capacity issues. Other technical domains, such as Network Support, may carry out the bulk of the relevant day-to-day duties but overall responsibility lies with the Capacity Management process. The process should encompass, for both the operational and the development environment:

• all hardware - from PCs, through file servers, up to mainframes and super-computers
• all networking equipment (LANs, WANs, bridges, routers etc.)
• all peripherals (bulk storage devices, printers etc.)
• all software - operating system and network software, in-house developments and purchased packages
• human resources, but only where a lack of human resources could result in a delay in end-to-end response time (e.g. overnight data backups not completed in time because no operators were present to load tapes) - in general human resource management is a line management responsibility, though the staffing of a Service Desk might well use identical Capacity Management techniques.

However the driving force for Capacity Management should be the business requirements of the organisation.

Figure 6.2 - Capacity Management and the business

Figure 6.2 shows that Capacity Management has a close, two-way relationship with the business strategy and planning processes within an organisation. On a regular basis, the long-term strategy of an organisation is encapsulated in an update of the business plans. The business plans are developed from the organisation's understanding of the external factors such as the competitive market-place, economic outlook and legislation, and its internal capability in terms of manpower, delivery capability etc.

Capacity Management needs to understand the long-term strategy of the business while providing information on the latest ideas, trends and technologies being developed by the suppliers of computing hardware and software.

The organisation's business plans dictate the specific IT/IS strategy and business plans, the contents of which Capacity Management needs to be familiar with, and to which Capacity Management needs to have had a large input. In the IT/IS specific business plans, particular technologies, hardware and software are identified, together with some indication of the timescale in which they are to be implemented.

For more information on the interface between the business plans and strategy, and how they need to be reflected in IS/IT specific business plans and strategy, see the ICT Infrastructure Management book.