This is often regarded as the paradigm of HA. It describes the cluster mechanism originally employed by the Digital's VAX computers. (The best description is contained in the much later openVMS documents [3]). The key element here is that when a cluster forms, it establishes the number of votes each cluster member has and compares that against the total available votes. If the forming cluster has under half (the quorum) it is unable to perform any operations and must wait until it attains over half the available votes (becomes quorate). Often votes are given to so called ``tie break'' resources like discs so that the formation of the cluster may be mediated solely by ownership of the tie-breaker resources.
The essential operational feature here is that the cluster control system must first fully recover from the failure (by establishing communication paths, cluster membership, voting and so on) before it may proceed to direct resource recovery.