Define the Server’s Arbitration Priority

Servers in a multi-server architecture may lose their connections with the other servers, for example, a Main server may lose its connection to a Standby server due to a network failure. When a Main server loses its connection to a Standby server, it can result in a Main-Main situation (or even Main-Main-Main situation if all network connections fail in a Triple Standby architecture). During a Main-Main situation, more than one server runs as a Main server. This means that when the connection between the servers is restored, the servers have to arbitrate to determine which server is to continue running as the Main server and which server is to switch to being a Standby server.

During the arbitration process, the servers use the following information to determine which server continues as Main:

1. Arbitration Priority setting in the servers’ configuration
2. Amount of time each server has been running as Main. The server that has been running as Main for the longest amount of time continues as the Main server.
3. Amount of time each server has been running (as either/both Main or Standby).The server that has been running the longest amount of time continues as the Main server.
4. The ASCII value of the servers’ node names. The server with the highest ASCII value for its name continues as the Main server.

These factors are considered in order, so the amount of time each server has been running is only considered in the arbitration process if the servers have identical Arbitration Priority settings.

You can use the Server Configuration Tool’s System Configuration>Partners settings to access and define the Arbitration Priority setting for a server. The Arbitration Priority setting is shown on the Miscellaneous tab.

The Arbitration Priority setting works by allowing you to enter a priority number. The server with the highest number is the server that continues to run as the Main server following a Main-Main situation. For example, if Server A has an Arbitration Priority of 0 and Server B has an Arbitration Priority of 1, and then Server B will be the Main server after a Main-Main situation has been resolved. Server A would be switched from Main to Standby as its Arbitration Priority number is lower than the Arbitration Priority number of Server B.