The Capacity and Availability Management process area involves establishing and maintaining capacity and availability at a justifiable cost and with an efficient use of resources. Capacity and availability management activities can be performed at different levels of the organization, including across different services. The Capacity and Availability Management process area involves the following activities:
- Establishing and maintaining a capacity and availability management strategy
- Providing and allocating resources appropriately
- Monitoring, analyzing, understanding, and reporting on current and future demand for services, use of resources, capacity, service system performance, and service availability
- Determining corrective actions to ensure appropriate capacity and availability while balancing costs against resources needed and supply against demand
“Capacity” is the degree to which one thing can support, hold, process, or produce another thing. In the context of services, capacity can refer to the maximum amount of service delivery or maximum number of service requests that a service system can handle successfully within a fixed period of time. Capacity is a quality attribute. The definition and measurement of capacity can differ for different types of services and service systems and can be defined in the service agreement. In addition, capacity definitions and measures can be derived from service agreements, rather than reflected there. If the service agreement has no explicit capacity requirements, it may still imply derived capacity requirements for the service or service system. For some services, capacity can be the maximum size, volume, or throughput of service system components.
Examples of capacity include the following:
- Number of vehicles requiring maintenance that can be received on the maintenance premises within a 24-hour period
- Number of loan application forms that can be processed within an 8-hour period
- Size or volume of a disk drive
- Square feet of floor space that can be cleaned per hour
- Number of pounds that a loader can hold at one time
- Total amount of fluid that can be absorbed by a service system component
- Number of calls per day that can be handled by a call center
- Number of appraisals that can be performed per year
As part of establishing the capacity and availability management strategy, the following are determined:
- Resources appropriate to manage
- Aspects of the service system that affect service availability and should be measured, monitored, analyzed, and managed
Examples of resources include staff, hardware, power, and available space.
“Availability” is the degree to which something is accessible and usable when needed. In the context of services, availability can refer to the set of times, places, and other circumstances in which services are to be delivered, service requests are to be honored, or other aspects of a service agreement are to be valid. Availability is a quality attribute. Different work groups can have different definitions and measurements of availability for different types of services and service systems and for various perspectives of availability (e.g., business perspective, end-user perspective, customer perspective, service provider perspective). The definition of availability requires an understanding of how service system components support service requirements for availability, which can be defined in the service agreement. In addition, availability requirements and measures can both depend on and affect other closely related quality attribute requirements, such as maintainability, reliability, sustainability, and security.
Examples of service system components for which availability can be a concern include the following:
- Anesthesia equipment
- Cafeteria staff
- Maintenance supplies
- Transportation components (e.g., cabs, buses, trucks, drivers)
- Call center staff
- Lead appraisers
Availability is one of the most visible indicators of service quality in the eyes of the end user and customer. For some services, understanding the relationships among attributes such as reliability and maintainability and availability is important to managing availability.
Availability of services can depend on the following:
- Availability of service system components
- Resilience of the service system to failure
- Quality of the maintenance performed on the service system
- Quality of the support provided to the service system
- Effectiveness of service processes
- Security practices
“Capacity management” is focused on how best to provide resources to meet service requirements. “Availability management” is focused on delivering a sustained level of availability to meet service requirements. However, at a high level, many of the best practices for capacity management and availability management are similar enough to be combined, and they become closely coupled. Capacity management provides the means for achieving sustained availability to meet service requirements. (For some services, it provides spare capacity and resilience as well.) The simultaneous production and consumption of services is one of the unique characteristics of services. This characteristic presents some challenges for managing the capacity and availability of services. If the capacity and availability to provide the service is not present when demand occurs, the customer must wait, resulting in costs of one kind or another (e.g., lower customer satisfaction, lost business as customers give up on waiting, financial penalties). Costs can also be associated with excess capacity when estimated demand does not occur (e.g., cost of staff on the payroll sitting idle, purchasing costs of excess capacity).
Examples of capacity management challenges include the following:
- Providing enough and the right kind of hotel rooms to meet demand without double booking or ending up with empty hotel rooms
- Providing enough baggage handlers for the volume of travelers at an airport without having excess or idle baggage handlers
Examples of availability management challenges include the following:
- Ensuring that landscaping services are delivered, landscaping equipment is maintained, and landscaping staff are able to take days off (e.g., holidays, annual leave) as defined in relevant agreements
- Monitoring the reliability of landscaping equipment and staff (e.g., the absentee rate among landscaping staff members)
- Determining corrective action when service availability drops below levels in the service agreement
Capacity and availability management includes establishing service system representations and using these representations for the following:
- Supporting negotiation of appropriate service agreements
- Making decisions
- Considering corrective actions
- Providing and allocating resources to meet current and future service requirements
“Service system representations,” such as models, simulations, diagrams, maps, and prototypes, provide insight into how a service system will behave given specific work volumes and varieties. These representations can be built using spreadsheets, commercial off-the-shelf (COTS) tools (e.g., simulation packages), or tools developed in house. For some services, the representations can be known as historical baselines, trend analyses, analytical models, analysis of waiting times in queues, simulation models, statistical models (e.g., regression models, time series models), causal models (e.g., probabilistic networks), or application sizing. The scope of capacity and availability management can be one service system or multiple service systems. If the service provider is operating multiple service systems, capacity and availability management processes can be performed independently on each discrete service system but the organization may realize reduced value.