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Availability Management assures that IT services are available when the customer needs them. Different areas of the business will have widely varying availability needs. Satisfying these disparate needs heavily influences system architecture, operational processes, and cost.

Key elements of Availability Management include:

• Availability - the % of the agreed service hours where the services were available
• Reliability - heavily influenced by architecture & design, reliability focuses on the prevention of failure and the ability to tolerate failures while still providing service.
• Maintainability - the ability of an IT system to be retained in or restored to an operational state.
• Serviceability - in ITIL terms this is support provided by external sources contracted to provide components of the IT infrastructure.
• Security - defined as the confidentiality, integrity, and availability of data associated with providing a service.

The degree of availability can be groups into three broad categories:

• High Availability: the ability to hide the effect of IT component failure from the user.
• Continuous Operation: minimizes or completely hides the effect of planned down time from the user.
• Continuous Availability: minimizes of completely hides the effect of ALL failures and planned downtime from the user.

A substantial number of metrics can be generated around availability. The metrics selected need to support specific objectives to avoid drowning in data. Care must be taken to account for the influence of what is being measured and how it is reported (see standards and metrics).

Other Links

• Service Level Management
• Capacity Management
• Availability Management
• Service Continuity Management (business continuity and disaster recovery)
• Financial Management of IT Services