The amount of time a repairable unit is not operating This can be due to being in a failed state, administrative delay, waiting for replacement parts to be shipped, or undergoing active repair
Period during which a computer, communications line or other device is not operating correctly because of mechanical or electronic failure (As opposed to available time, idle time or stand-by time )
A period of time during which a computer is not functioning It is inoperable because of temporary or permanent failure of hardware or software, or when routine hardware or software maintenance procedures are indicated