A server crashes on the average once in 30 days, that is, the Mean Time…
2016
A server crashes on the average once in 30 days, that is, the Mean Time Between Failures (MTBF) is 30 days. When this happens, it takes 12 hours to reboot it, that is, the Mean Time to Repair (MTTR) is 12 hours. The availability of server with these reliability data values is approximately :
- A.
96.3%
- B.
97.3%
- C.
98.3%
- D.
99.3%
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Correct answer: C
Answer: 98.3%
Key formula: Availability = MTBF / (MTBF + MTTR).
Convert MTTR to the same units as MTBF: 12 hours = 0.5 day.
Compute availability: 30 / (30 + 0.5) = 30 / 30.5 ≈ 0.983606557.
Express as a percentage: 0.983606557 × 100 ≈ 98.36%, which rounds to 98.3%.
Therefore the correct availability is approximately 98.3%.