Responding to an unplanned outage

If your database management software or cluster management software detects that a database server has failed, your database solution must respond to that failure as quickly and as smoothly as possible. Your database solution must attempt to shield user applications from the failure by rerouting workload, if possible, and failover to a secondary or standby database, if one is available.

1. Identify, bring online, and initialize a secondary database server to take over operations for the failed database server.

   If you are using DB2® High Availability Disaster Recover (HADR) to manage primary and standby database servers, HADR will manage keeping the standby database synchronized with the primary database; and HADR will manage the takeover of the primary database by the standby database.

2. Reroute user application workload to the secondary database server.

   DB2 client reroute can automatically reroute client application away from a failed database server to a secondary database server previously identified and configured for this purpose.

3. Remove the failed database server from the system to repair it.

   Once the user applications have been rerouted to a secondary or standby database server, the failed database server can not handle any client application requests until it has been restarted or otherwise repaired. For example, if the cause of the failure on the primary database was that a database instance terminated unexpectedly, the DB2 fault monitor facility will automatically restart it.