Before Forcing a Quorum
When a cluster contains enough reachable servers, but not enough non-empty servers to form a quorum, an administrator may force a quorum. Read this topic first.
Check Safety
Before forcing a quorum, first verify that it is safe to do so.
- If none of the unreachable servers are running, it is safe to force a quorum.
- If any server processes are actually running but unreachable, then it is
not safe to force a quorum. Those servers could contain more recent message data than the quorum candidates, and forcing a quorum would forfeit those messages.
Instead, restore reachability by repairing the network problem. Then the quorum can reform itself without administrator intervention.
Example: Persistence Servers, Forcing a Quorum
Consider a persistence cluster that defines three servers. Only two servers are reachable. The third server is unreachable.
The two reachable servers cannot form a quorum because s2 is empty (see Quorum Conditions General Rule). If the administrator determines that s1 has actually exited, then it is safe to force a quorum. The administrator can explicitly force a quorum using the force quorum command icon in the cluster row of the persistence clusters status table.
If, on the other hand, s1 is still running, it could hold a more recent history state than s3 (the candidate with the most recent history state). Instead of forcing a quorum, the administrator should endeavor to repair the network problem that partitions s1 from the other candidates.
See Also: Force Quorum