N minus 1
This strategy attempts to provide an "easy button" for small server groups that grow from one to three members. The n-1 strategy implies that a quorum exists only when all, or all but one, member servers are submitting ballots. When the number of member servers in the group is 1 or 2 the strategy behaves the same as none; when the number of servers is 3, it behaves the same as majority.
When to use this strategy:
Use this when you intend to deploy one, two, or three member servers and you want the system to reasonably adapt to the change in the number of member servers.