Increasingly, activities business and government, among others rely on data-processing resources to fulfill their missions. The availability of these resources (that is, their ability to deliver the specified services) and the degree of confidence users can place in the availability of these services, therefore, become requirements for and essential properties of these systems.
The following few definitions help to crystallize the important concept of system reliability:
Reliability allows a user to have a justified confidence in the services delivered by the system
Reliability is the time-bound property and characteristics of an entity which give it the ability to satisfy needs both explicit and implicit for a given period of time under specified conditions (X50-125, standard of management of quality and quality assurance, standard ISO 8402)
Reliability is the collection of a product's capabilities, enabling it to provide the specified performance, at the time desired, during a specified time period, without damage to itself or its environment.
Any function of a system or of a subsystem for which the property of reliability is a necessity is known as a critical function.
A system's reliability is characterized by a number of properties:
Reliability. A measure of the continuity of the services rendered. This is a common property of critical systems, such as the data processing or embedded systems used for air traffic control, monetary exchange systems, military command-and-control systems, and so forth.
Availability. A measure of the system's ability to deliver its capabilities when needed. The availability of a system...
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