Connection failover allows an application to connect to an alternate, or backup, database server if the primary database is unavailable, for example, because of a hardware failure or traffic overload. Connection failover ensures that the data on which your critical .NET applications depend is always available.
For example, Figure 1 shows an environment with multiple database servers. Database Server A is designated as the primary database server, Database Server B is the first alternate server, and Database Server C is the second alternate server.
First, the application attempts to connect to the primary database, Database Server A (1). If connection failover is enabled and Database Server A fails to accept the connection, the application attempts to connect to Database Server B (
2). If that connection attempt also fails, the application attempts to connect to Database Server C (
3).