Nnodes in size to remain operational, at least
(N/2)+1nodes must be up and running, and be in contact with each other.
Nis the number of nodes in the cluster. For a 3-node a majority is 2; for a 4-node cluster a majority is 3. Therefore a 3-node cluster can tolerate the failure of a single node. However a 4-node cluster can also only tolerate a failure of a single node.