Quorum Computation

Given a cluster size of N nodes, which tolerates f failures according to, quorum size should satisfies the following:

  f = argmax ( N >= 3f+1 )

where Q is the size of the quorum such that, any two subsets q1, q2 of size Q, intersect in at least f+1 nodes.

NOTE: that this is different from N-f (the number of correct nodes), when N=3f+3. That is, we have two extra nodes above the minimum required to tolerate f failures.