Starting SQL Server in Single-User Mode

Under certain circumstances, you may have to start an instance of Microsoft SQL Server in single-user mode by using the startup option -m. For example, you may want to change server configuration options or recover a damaged master database or other system database. Both actions require starting an instance of SQL Server in single-user mode.

When you start an instance of SQL Server in single-user mode, note the following:

• Only one user can connect to the server.
  
• The CHECKPOINT process is not executed. By default, it is executed automatically at startup.
  

Note:
Stop the SQL Server Agent service before connecting to an instance of SQL Server in single-user mode; otherwise, the SQL Server Agent service uses the connection, thereby blocking it.