Downtime

The term downtime is used to refer to periods when a system is unavailable.Downtime or outage duration refers to a period of time that a system fails to provide or perform its primary function. Reliability, availability, recovery, and unavailability are related concepts.The unavailability is the proportion of a time-span that a system is unavailable or offline.This is usually a result of the system failing to function because of an unplanned event, or because of routine maintenance (a planned event). The term downtime is used to refer to periods when a system is unavailable.Downtime or outage duration refers to a period of time that a system fails to provide or perform its primary function. Reliability, availability, recovery, and unavailability are related concepts.The unavailability is the proportion of a time-span that a system is unavailable or offline.This is usually a result of the system failing to function because of an unplanned event, or because of routine maintenance (a planned event). The term is commonly applied to networks and servers. The common reasons for unplanned outages are system failures (such as a crash) or communications failures (commonly known as network outage).