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Question 61Asked in UGC NET Computer Science, June 2016 (Paper II & III, Selected Questions)

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…

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 :
  1. A96.3%
  2. B97.3%
  3. C98.3%
  4. D99.3%
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Correct answer: (C) 98.3%

Explanation

If we let A represent availability, then the simplest formula for availability A = uptime/(uptime + downtime) MTBF is mean time between failures A = MTTR is mean time to repair A = MTBF/(MTBF + MTTR) So MTBF = 30 days = 30 × 24 = 720 hr A = 720/(720 + 12) = 98.3%

From UGC NET Computer Science PYQ, June 2016 (Paper II & III, Selected Questions)

This is question 61 of UGC NET Computer Science PYQ, June 2016 (Paper II & III, Selected Questions). See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.