I was trying to solve the following question in software architecture.A software system crashed 20 times in an year and for each crash, it takes 2 minutes to restart. Calculate availability in that yearI used the formula MTBF/(MTBF+MTTR) as given MTTR =2 minutes. But how can I calculate MTBF and availability?MTBF = Mean Time Between Failures MTTR = Mean Time To RepairUpdate : I did it likeMTBF = 365*24*60-40/ 20, MTTR = 2*20
What's the equation to use for finding availability in software architecture?
architecture;software
You would normally assume a system has 24/7 (i.e. 'round the clock) availability.Therefore, in minutes, it needs to be available for 365 (days) * 24 (hours) * 60 (minutes) = 525600 minutes.Your MTBF then becomes fairly simple, it's just that amount of time divided by the number of failures (20).  Therefore: MTBF = 525600 / 20 =26280 (minutes MTBF).Then applying  MTBF/(MTBF+MTTR) gives: 26280 (MTBF) / (26280+2) = 0.99992390229054105471425310098166 - or approx. 99.99% availability.Hope that makes sense!