Why Capacity Planning Is Seldom Done Well
Two activities in the management of infrastructures historically are not done well (if done at all):
The reason for poor, little, or no documentation is straightforward: Few individuals have the desire or the ability to produce quality technical writing. Managers don't always help the situation; many of them don't emphasize the importance of documentation, so the writing of procedures drops to a low priority and is often overlooked or forgotten until that documentation is needed in a critical situation.
But what of capacity planning? Almost every infrastructure manager and most analysts will acknowledge the importance of ensuring that adequate capacity is planned for and provided. And there's nothing inherently difficult or complex about developing a sound capacity-planning program. So why is it so seldom done well?
Why Capacity Planning Fails
In my experience, there are seven primary reasons why many infrastructures fail at implementing an effective capacity planning program:
Analysts are too busy with day-to-day activities.
Users aren't interested in predicting future workloads.
Users who are interested can't forecast accurately.
Capacity planners may be reluctant to use effective measuring tools.
Corporate or IT directions may change from year to year.
Planning is typically not part of an infrastructure culture.
Managers sometimes confuse capacity management with capacity planning.
The following sections discuss each of these reasons and suggest corrective actions.
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. The systems analysts can be subdivided further:
Systems administrators deal with server capacity
Network administrators deal with network bandwidths
Database administrators deal with the amounts and sizes of disk storage and databases
But these two broad groups of analystssystems analysts and programmer analystsare 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.
Users Aren't 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 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:
By explaining to end users that accurate workload forecasts assist in justifying additional computer capacity to ensure acceptable system performance in the future
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
Users Who Are Interested Can't Forecast Accurately
Some end users clearly understand the need to forecast workload increases to ensure acceptable future performance, but don't have the skills, experience, training, or tools to do so. Joint consultations with both groups of developers and capacity plannerswho can show users how to forecast accuratelycan help to alleviate this drawback.
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 inherited. Many feel comfortable using only old or outdated techniques. Cross-training, documentation, consultation with the vendor, and turnover from prior users of the tool can help overcome this reluctance.
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's true that corporate mergers, acquisitions, and redirections may dramatically alter a capacity plan, the fact is that the process of developing the plan has inherent benefits regardless of corporate direction. Not least among these benefits is the improved communication and partnering that often occurs between IT and its customers.
Planning Is Typically Not Part of an Infrastructure Culture
My many years of experience with infrastructures bears out this statement. Most infrastructures I've 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 situation is slowly changing, with world-class infrastructures realizing the necessity and benefits of sound capacity planning. A dedicated planning group for infrastructures is suggested.
Managers Sometimes Confuse Capacity Management and 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.