Reference
Availability Percentages
Availability percentages measured in 9s of uptime, qualified by (rounded) expected downtime
| Availability % | Downtime per year | Downtime per month | Downtime per week | Downtime per day |
|---|---|---|---|---|
| 90% | 37 days | 4400 minutes (73 hours) | 1000 minutes (17 hours) | 140 minutes |
| 99% | 3.7 days | 440 minutes (7.3 hours) | 100 minutes (1.7 hours) | 14 minutes |
| 99.5% | 1.8 days | 220 minutes (3.7 hours) | 50 minutes | 7.2 minutes |
| 99.9% | 8.7 hours | 43.8 minutes | 10 minutes | 1.4 minutes |
| 99.99% | 53 minutes | 4.4 minutes | 1.0 minutes | 8.6 seconds |
Source: Wikipedia; High availability