Determining when it is necessary to switch from the active to the standby database depends on the requirements of your applications.
In general, you should not switch when the active data server experiences a transient failure. A transient failure is a failure from which the Adaptive Server recovers upon restarting with no need for additional recovery steps. You probably should switch if the active database will be unavailable for a long period of time.
Determining when to switch depends on issues such as how much recovery the active database requires, to what degree the active and standby databases are in sync, and how much downtime your users or applications can tolerate.
You may also want to switch the roles of the active and standby databases to perform planned maintenance on the active database or its data server.
