Slides - Åbo Akademi

More Definitions
Failure rate (or failure intensity): the number of failures per time
unit (hour, second, ...) or per natural unit (transaction, run, ...)
• can be considered as an alternative way of expressing reliability
Availability: the ability of a system to be in a state to deliver
correct service under given conditions at a specified instant of time
• usually measured by the average (over time) probability that a
system is operational in a specified environment
Maintainability: the ability of a system to be restored to a state in
which it can deliver correct service
• usually measured by the probability that maintenance of the
system will restore it within a given time period