As someone else said, your math is off. Your point is still reasonable, though. The uptime.is website is a handy resource for these calculations. For example,

As someone else said, your math is off. Your point is still reasonable, though. The uptime.is website is a handy resource for these calculations. For example, http://uptime.is/99.9 http://uptime.is/99.9 says "SLA level of 99.9 % uptime/availability results in the following periods of allowed downtime/unavailability: Daily: 1m 26s Weekly: 10m 4s Monthly: 43m 49s Quarterly: 2h 11m 29s Yearly: 8h 45m 56s"