How to: Manually Fail Over a Database Mirroring Session (SQL Server Management Studio)
When the mirrored database is synchronized (that is, when the database is in the SYNCHRONIZED state), the database owner can initiate manual failover to the mirror server.
During a manual failover, the principal and mirror server roles are swapped for the database on which the failover occurs. The mirror database becomes the principal database and the principal database becomes the mirror. For example, the following table shows the how a manual failover swaps the roles of two mirroring partners: SQLDBENGINE0_1 and SQLDBENGINE0_2.
Note that the server roles for other database mirroring sessions are not affected. For more information, see Manual Failover.
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.
If you have modified any properties since opening the Mirroring page, those changes will not be saved.
The dialog box closes automatically.