Availability

According to ITIL, availability is defined as "Ability of an IT service or other configuration item to perform its agreed function when required. Availability is determined by reliability, maintainability, serviceability, performance, and security".

Availability management is defined as "The process responsible for ensuring that IT services meet the current and future availability needs of the business in a costeffective and timely manner. Availability management defines, analyses, plans, measures and improves all aspects of the availability of IT services, and ensures that all IT infrastructures, processes, tools, roles etc. are appropriate for the agreed service level targets for availability".