Meaning of “five nines” in the English Dictionary

business-english dictionary

"five nines" in Business English

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five ninesnoun [ plural ]

uk us also five nines reliability IT

99.999 percent: the percentage of time that a computer system should work without failing:

In the computer industry, the challenging target is "five nines" or 99.999% - an average annual downtime of five minutes.
five nines availability/uptime

(Definition of “five nines” from the Cambridge Business English Dictionary © Cambridge University Press)