廣義的可靠度 = 可恃性(dependability)
可靠度=時間品質(quality over time) = 時間性能(performance over time)
可靠度(Reliability)定義:
the ability of an item to perform a required function under given conditions for a given time interval.
(software) the ability of equipment to prevent or correct errors.
(server) the system's ability to operate continuously without failure and to maintain data integrity.
the probability that an engineering system will perform its intended function satisfactorily (from the viewpoint of the customer) for its intended life under specified environmental and operating conditions.
維護度(Maintainability)定義:
(general) the ability of an item under given conditions of use, to be retained in, or restored to, a state in which it can perform a required function, when maintenance is performed under given conditions and using stated procedures and resources.
characteristic of design and installation which determines the probability that a failed equipment, machine, or system can be restored to its normal operable state within a given timeframe, using the prescribed practices and procedures. Its two components are serviceability (ease of conducting scheduled inspections and servicing) and repairability (ease of restoring service after a failure).
the probability that maintenance of the system will retain the system in, or restore it to, a specified condition within a given time period.
服務度(Serviceability)定義:
(computer) the measure of and the set of the features that support the ease and speed of which corrective maintenance and preventive maintenance can be conducted on a system.
(computer) the ease with which system administrators can diagnose problems, detect components likely to fail, and repair failing components within the equipment.
(server) the time it takes to restore a system to service following a system failure.
可用度(Availability)定義:
the ability of an item to be in a state to perform a required function under given conditions at a given instant of time or in average over a given time interval, assuming that the required external resources are provided.
the "uptime" of the equipment, the ability of the equipment to recover from errors, or the ability of the equipment to remain operational during and after an error.
(server) the ability of a system to recover to an operational state after a failure, with minimal impact.
the probability that the system is operating satisfactorily at any time, and it depends on the reliability and maintainability.