Typical availability - five 9s

In service level agreements (SLAs) usually there is a nice number given on availability. No one will guarantee 100% of uptime, but like 99%. Over a year this means quite some downtime.

Microsoft claims to aim to keep their systems at 99.999% uptime (except planned downtime). So, during a whole year such a system should not fail for more than about 5 minutes.

Sources:

Keywords:
Uptime, SLA

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