IT Management Reference Guide

This series of articles will focus on how to plan for the adequate capacity of computer resources within an infrastructure. Just as your perception of whether a cup is either half full or half empty may indicate whether you are an optimist or a pessimist, so also may a person's view of resource capacity indicate his or her business perception of IT. For example, a server operating at 60% capacity may be great news to a performance specialist who is trying to optimally tune response times. But, to an IT financial analyst trying to optimize resources from a cost standpoint, this may be disturbing news of unused resources and wasted costs. This series explains and bridges these two perspectives. In this initial segment I begin with a formal definition of capacity planning and then offer seven common reasons that this process is seldom done very well in most infrastructures.

Definition of Capacity Planning

As its name implies, the systems management discipline of capacity planning involves the planning of various kinds of resource capacities for an infrastructure, and is defined as follows:

capacity planning -- a process to predict the types, quantities, and timing of critical resource capacities that are needed within an infrastructure to meet accurately forecasted workloads.

As we will see, ensuring adequate capacity involves four key elements that are underscored in this definition:

• The type of resource capacities required, such as servers, disk space, or bandwidth

• The size or quantities of the resource in question

• The exact timing of when the additional capacity is needed

• Decisions about capacity that are based on sound, thorough forecasts of anticipated workload demands

Later in parts two and three of this series we will look at the steps necessary to design an effective capacity planning program. These four elements are an integral part of such a process. But first we will discuss why capacity planning is seldom done well in most infrastructure organizations.

Why Capacity Planning Is Seldom Done Well

There are two activities in the management of infrastructures that historically are not done well, if at all. These are documentation and capacity planning. The reason for poor, little, or no documentation is straightforward. Few individuals have the desire or the ability to produce quality technical writing. Managers do not always help the situation—many of them do not emphasize the importance of documentation, so the writing of procedures drops to a low priority and is often overlooked and forgotten until the time when it is needed in a critical situation.

But what of capacity planning? Almost every infrastructure manger and most analysts will acknowledge the importance of ensuring that adequate capacity is planned for and provided. There is nothing inherently difficult or complex about developing a sound capacity planning program. So why is it so seldom done well?

In my experience there are seven primary reasons why many infrastructures fail at implementing an effective capacity planning program (see Figure 1). I will discuss each of these reasons and suggest corrective actions.

Figure 1 Reasons Why Capacity Planning Is Seldom Done Well

1. Analysts are too busy with day-to-day activities.

The two groups of people who need to be most involved with an effective capacity planning process are systems analysts from the infrastructure area and programmer analysts from the application development area. But these two groups of analysts are typically the ones most involved with the day-to-day activities of maintenance, troubleshooting, tuning, and new installations. Little time is set aside for planning activities.

The best way to combat this focus on the tactical is to assign a group within the infrastructure to be responsible for capacity planning. It may start out with only one person designated as the process owner. This individual should be empowered to negotiate with developers and users on capacity planning issues, always being assured of executive support from the development side.

2. Users are not interested in predicting future workloads.

Predicting accurate future workloads is one of the cornerstones of a worthwhile capacity plan. But just as many IT professionals tend to focus on tactical issues, so also do end-users. Their emphasis is usually on the here and now, not on future growth in workloads.

Developers can help capacity planners mitigate this tendency in two ways: first, by explaining to end-users how accurate workload forecasts will assist in justifying additional computer capacity to ensure acceptable system performance in the future; second, by working with capacity planners to simplify the future workload worksheet to make it easier for users to understand it and to fill it out.

3. Users who are interested in predicting future workloads cannot forecast accurately.

Some end-users clearly understand the need to forecast workload increases to ensure acceptable future performance, but do not have the skills, experience, or tools to do so. Joint consultations with both developers and capacity planners who can show users how to do this can help to alleviate this drawback.

4. Capacity planners may be reluctant to use effective measuring tools.

Newly appointed capacity planners are sometimes reluctant to use new or complex measurement tools that they may have just inherited. Cross-training, documentation, consultation with the vendor, and turnover from prior users of the tool can help overcome this reluctance.

5. Corporate or IT directions may change from year to year.

One of the most frequent reasons I hear for the lack of comprehensive capacity plans is that strategic directions within a corporation and even an IT organization change so rapidly that any attempt at strategic capacity planning becomes futile. While it is true that corporate mergers, acquisitions, and redirections may dramatically alter a capacity plan, the fact is that the actual process of developing the plan has inherent benefits. I will discuss some of these benefits later in this chapter.

6. Planning is typically not part of an infrastructure culture.

My many years of experience with infrastructures bears this out. Most infrastructures I worked with were created to manage the day-to-day tactical operations of an IT production environment. What little planning was done was usually at a low priority and often focused mainly on budget planning.

Many infrastructures today still have no formal planning activities chartered within their groups, leaving all technical planning to other areas inside IT. This is slowly changing with world-class infrastructures realizing the necessity and benefits of sound capacity planning. A dedicated planning group for infrastructures is suggested.

7. Managers sometimes mistake capacity management for capacity planning.

Capacity management involves optimizing the utilization or performance of infrastructure resources. Managing disk space to ensure that maximum use is occurring is a common example, but this is not capacity planning. Capacity management is a tactical activity that focuses on the present. Capacity planning is a strategic activity that focuses on the future. Understanding this difference should help minimize confusion between the two.

Understanding and avoiding these seven common reasons for why capacity planning is seldom done well can help build a firmer foundation from which to develop a successful capacity planning program. In Part Two of this series we will look at the set of steps required to implement such a program.

References

Schiesser, Rich, IT Systems Management, Prentice Hall, 2002