Probability, Statistics, Distributed Systems, Software Engineering, Interview Questions.
is down is given as ‘p’. How many replicas will be required so that probability that at-least majority of the replicas are up is 99.99%? Let the number of replicas be N (odd). For majority, it is (N+1)/2. Probability that 'k' servers are up = (N chooses k)*(1-p)^k*p^(N-k) i.e. choose k out of N