Fig. 5: Data Center Tiers
|
|
Tier I |
Tier II |
Tier III |
Tier IV |
|
Typical Availability |
99.67% |
99.75% |
99.98% |
99.99% |
|
Annual IT Downtime |
28.8 hours |
22.0 hours |
1.6 hours |
0.8 hours |
|
Concurrent Maintenance |
No |
No |
Yes |
Yes |
|
Fault Tolerance |
No |
No |
No |
Yes |
|
UPS Configuration |
Capacity N |
N+1
Redundant |
Distributed Redundant |
2N or 2N+1 |
|