This technical document is about Manual failover in SQL Server
To achieve maximum availability we need to configure Mirror Server which requires for Failover in case of Primary server is not available.
When Primary server availability is assured then we again failover back to Primary. We need to perform this activity manually.
To manually fail over database mirroring :
Connect to the principal server instance and, in the Object Explorer pane, click the server name to expand the server tree.
Expand Databases, and select the database to be failed over.
Right-click the database, select Tasks, and then click Mirror. This opens the Mirroring page of the Database Properties dialog box.
A confirmation box appears. The principal server begins by trying to connect to the mirror server by using Windows Authentication. If Windows Authentication does not work, the principal server displays the Connect to Server dialog box. If the mirror server uses SQL Server Authentication, select SQL Server Authentication in the Authentication box. In the Login text box, specify the login account to connect with on the mirror server, and in the Password text box, specify the password for that account.
If failover succeeds, the Database Properties dialog box closes. The mirror database becomes the principal database and the principal database becomes the mirror.
If failover fails, an error message is displayed and the dialog box remains open.