Pause or Resume a Database Mirroring Session

We can pause and resume any Database Mirroring any time. Pausing mirroring preserves the mirroring state. Sometime pausing is very useful to improve the performance of the principal server. Pausing sets the state of the mirroring session to SUSPENDED, and the mirror database no longer updated with the principal database. 

We should resume the mirroring session quickly because as long as the session is paused then transaction log cannot be truncated. If the session is paused for a long time the log file may be grow large causing the database unavailable.

When a session is paused the  principal database is remains available.

Steps to pause and resume a database mirroring session follow below steps:

1. In Object explorer, connect to the principal server and click the server name to expand.
   
   
2. click on the Database and select the database.
   
   
3. Now right click the database, select Tasks, and then click on Mirror. Now, it will opens the Mirroring page of the Database Properties dialog box.
   
   
4. To pause the session, click Pause.
   A Confirmation message will come, if you click Yes, the session is paused, and the button changes to Resume.
   
   For more information about the impact of pausing a session, see Pausing and Resuming Database Mirroring.
5. To resume the session, click Resume.
   
   Ref: MSDN