As per techtarget definition:
Capacity planning is the science and art of estimating the space, computer hardware, software and connection infrastructure resources that will be needed over some future period of time.
A typical capacity concern of many enterprises is whether resources will be in place to handle an increasing number of requests as the number of users or interactions increase.
The aim of the capacity planner is to plan so well that new capacity is added just in time to meet the anticipated need but not so early that resources go unused for a long period. The successful capacity planner is one that makes the trade-offs between the present and the future that overall prove to be the most cost-efficient.
Basic steps of capacity planning:
- Determine Service Level Requirements
The first step in the capacity planning process is to categorize the work done by systems and to quantify users’ expectations for how that work gets done.
- Analyze Current Capacity
Next, the current capacity of the system must be analyzed to determine how it is meeting the needs of the users.
- Planning for the future
Finally, using forecasts of future business activity, future system requirements are determined. Implementing the required changes in system configuration will ensure that sufficient capacity will be available to maintain service levels, even as circumstances change in the future.
Capacity planning activities:
- capacity analysis and prediction for storage, database, and application servers;
- designing architectures to easily add and measure capacity.
- handling sudden spikes.
- predicting exponential and explosive growth.
Do not confuse performance with capacity: performance is based more on human work, and capacity is based more on computer resources.