More server capacity equals better performance, right? This rule is simple and still in use as a substitute for a true capacity management policy in some organizations. Frankly, when IT Operations are facing a booming business demand, there is little time to argue about the difference between performance and capacity and one is always tempted to apply the same old rule and add more capacity. Moreover, it works. Until next time…
Indeed, there is always a turning point when the rule fails. Performance problems appear that can't be solved by adding new capacity, and the accumulation of resources ends up alarming somebody at the C level. It is time to change to a better rule and realize that performance and capacity are not the same.
Different Goals and Scopes
The goal of capacity management is to provide the right resources at the right time for the right price. The focus is on "how many" resources are required and what actions need to be taken. The challenge is to improve resource efficiency without impacting the business.
The goal of performance management, on the other hand, is to monitor the performance of systems, to ensure that service level requirements are met, and to take corrective action if necessary. The focus is on "what" is happening and how it can be improved, e.g. by solving problems and getting rid of bottlenecks that do not necessarily exist due to a lack of capacity.
Strong Interdependencies
The reason why people sometimes find it hard to differentiate one from the other is that capacity and performance management are strongly interdependent:
- Capacity management encompasses capacity planning and performance management.
- Capacity management usually comes after performance management, the first step being to switch on the light, report on resource utilization and provide visibility over costs and risks.
- Performance management and capacity planning teams are usually contributing to a single capacity management process.
- Even capacity planning activities rely on performance management activities and tools as they need regular reports for trend analysis and tracking against their forecasts.
Conclusion
The challenge of capacity management is very often a cultural one. Once resource efficiency has been identified as a key performance indicator, organizations often find it difficult to mature on capacity management and face two opposite risks: Either to start from performance management and fail to give capacity the right position in the management system, or to start from a modeling perspective and fail to connect capacity management with the operations system.
Indeed, capacity management effectiveness depends on an organization’s ability to reconcile the technical world of performance analysts and the management perspective of business plans and capacity models.
