System availability
From Zenitel Wiki
System availability
System Availability
- The percentage of time that the system can perform its intended function
System Availability = 1 – System Downtime
Downtime per year
| Availability | Nines | Downtime | |
| 90% | 1 | 36.5 | days/year |
| 99% | 2 | 3.65 | DAys/year |
| 99.9% | 3 | 8.78 | hours/year |
| 99.99% | 4 | 52 | minutes/year |
| 99.999% | 5 | 5 | minutes/year |