Law
Availability is dominated by repair time
Everyone who can chooses to divide MTTR. MTTR itself has three parts: detect + decide + act, and detection usually dominates.
- Mean time between failures
- average time between failures
- Mean time to repair
- detect + decide + act
How it behaves
One input on the horizontal axis, the others held fixed.
Data table
| Repair time MTTR | Availability |
|---|---|
| 60 s | 100% |
| 65.7 s | 100% |
| 72 s | 100% |
| 78.8 s | 100% |
| 86.3 s | 100% |
| 94.5 s | 100% |
| 104 s | 100% |
| 113 s | 100% |
| 124 s | 100% |
| 136 s | 100% |
| 149 s | 100% |
| 163 s | 100% |
| 179 s | 100% |
| 196 s | 100% |
| 214 s | 100% |
| 235 s | 100% |
| 257 s | 100% |
| 281 s | 100% |
| 308 s | 100% |
| 337 s | 100% |
| 370 s | 100% |
| 405 s | 100% |
| 443 s | 100% |
| 485 s | 100% |
| 532 s | 100% |
| 582 s | 100% |
| 638 s | 100% |
| 698 s | 100% |
| 765 s | 100% |
| 838 s | 100% |
| 917 s | 100% |
| 1,000 s | 100% |
| 1,100 s | 100% |
| 1,200 s | 100% |
| 1,320 s | 99.9% |
| 1,450 s | 99.9% |
| 1,580 s | 99.9% |
| 1,730 s | 99.9% |
| 1,900 s | 99.9% |
| 2,080 s | 99.9% |
| 2,280 s | 99.9% |
| 2,490 s | 99.9% |
| 2,730 s | 99.9% |
| 2,990 s | 99.9% |
| 3,280 s | 99.9% |
| 3,590 s | 99.9% |
| 3,930 s | 99.8% |
| 4,300 s | 99.8% |
| 4,710 s | 99.8% |
| 5,160 s | 99.8% |
| 5,650 s | 99.8% |
| 6,190 s | 99.8% |
| 6,780 s | 99.7% |
| 7,420 s | 99.7% |
| 8,130 s | 99.7% |
| 8,900 s | 99.7% |
| 9,750 s | 99.6% |
| 10,700 s | 99.6% |
| 11,700 s | 99.6% |
| 12,800 s | 99.5% |
| 14,000 s | 99.5% |
| 15,400 s | 99.4% |
| 16,800 s | 99.4% |
| 18,400 s | 99.3% |
| 20,200 s | 99.2% |
| 22,100 s | 99.2% |
| 24,200 s | 99.1% |
| 26,500 s | 99% |
| 29,000 s | 98.9% |
| 31,800 s | 98.8% |
| 34,800 s | 98.7% |
| 38,100 s | 98.6% |
| 41,800 s | 98.4% |
| 45,700 s | 98.3% |
| 50,100 s | 98.1% |
| 54,800 s | 97.9% |
| 60,100 s | 97.7% |
| 65,800 s | 97.5% |
| 72,000 s | 97.3% |
| 78,900 s | 97% |
| 86,400 s | 96.8% |
Worked examples, recomputed
Every number the mechanisms quote for this relationship is recomputed from it, so none of them disagrees with it.
Where it appears
Each mechanism states it in its own names. The general symbol each name stands for is shown with it.
- Fault Tolerance & Delivery Semantics
What is the cheapest thing that can be safely done twice?