Establish and Document the Application's Capacity Plan and Performance Baselines

This chapter explains how to establish and document how much demand an Application must handle, how it normally performs, and what happens as demand grows.

Establish the Capacity Plan and Performance Baselines

Establish, with the Operations and Support Team(s) and the IT Application Owner:

• Expected load and growth: the volumes the Application must handle, such as users, transactions, data growth, and peak periods, starting from the initial estimate captured with the Application’s requirements and refined with actual Production experience.

• Performance baselines: how the Application normally performs, for example response times, throughput, and resource utilization, using results from performance testing and early Production operation.

• Capacity thresholds and actions: the thresholds at which capacity must be added or performance investigated, and the actions each triggers, aligned with the Application’s monitoring and alerting.

• Constraints: the components most likely to limit capacity, and any limits imposed by vendors or licenses.

Document and Share the Capacity Plan and Baselines

Record the capacity plan, performance baselines, thresholds, and actions in the Operational section of the Application Documentation, linked to the performance non-functional requirements and to the monitoring thresholds. Review them whenever demand changes significantly, and with every Release that may affect performance.

Best Practice: Establish and Document the Application’s Capacity Plan and Performance Baselines

It is a best practice to both establish and document the solution for an Application’s capacity: define expected load and growth, record normal performance baselines, and set capacity thresholds with the actions they trigger, reviewing them as demand and the Application change.

Benefits: Known baselines make performance problems recognizable immediately, because normal is defined. A capacity plan with thresholds lets the enterprise add capacity before demand exceeds it, avoiding both slowdowns at peak periods and money wasted on capacity that is never used.

Connections to Related IF4IT Practices and Inventories

The IT Operating Environments Best Practices addresses governing environment capacity, consumption, and resource guardrails. The Non-Functional Requirements (NFRs) Framework for Software Systems addresses performance and scalability requirements.