Discovery Mode

A cluster member uses discovery mode to determine whether it should come online as the active node or a standby node. A cluster member enters discovery mode in any of the following situations:

Each standby node in a cluster polls the active node periodically to draw down synchronization transactions. If the standby node does not receive a response within 10 seconds, it assumes the active node has failed and it goes into discovery mode to find out the status of other nodes in the cluster.

After entering discovery mode, a server takes one of the actions shown in the following table, depending on the status of the other cluster members:

Table 1. Discovery mode actions

Status of other Cluster Members

Action Taken by Server in Discovery Mode

One cluster member is already active.

The server comes online as a standby node.

No cluster member is active and no other server is in discovery mode.

The server comes online as the active node and takes control of the cluster.

No cluster member is active and one or more other servers are in discovery mode.

The rankings on the Cluster Setup page of the Server screen serve as a tie-breaker.