Five Nines

/faɪv naɪnz/ · Noun · Development · Origin: 1990

Definitions

  1. A measure of system availability equal to 99.999%, allowing no more than 5 minutes and 15 seconds of downtime per year.

    In plain English: A promise that a service will be working 99.999% of the time. That leaves only about 5 minutes of downtime in an entire year — an extremely high bar.

    Example: "We promised five nines in the SLA, which means our entire annual error budget is about five minutes — one bad deploy could blow it."

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