Quorum Conditions General Rule

A valid quorum ensures correct replication and fault tolerance. As a general rule, a group of candidate servers must satisfy all three of the following conditions to form a valid quorum.

(For special exceptions, see Quorum Behaviors.)

  • Majority:  The number of candidate servers that satisfy these conditions must be strictly greater than half of the number of servers in the cluster definition (that is, a simple majority).
  • Reachable:  A majority of the defined servers must be running and able to communicate with one another.
  • Non-Empty:  A majority of the defined servers must be non-empty. (A server process is empty when its process starts or restarts without loading saved state. A server that has successfully joined a quorum is no longer empty.)
Related concepts