How to Restore a Microsoft SQL Server Master Database

Applies to…

  • DxEnterprise
  • Microsoft SQL Server


Restoring the Microsoft SQL Server master database running on a DxEnterprise cluster.


This is very much the same as how you would do so with a stand-alone instance. There are really just two additional steps you need to take to successfully restore a master database:

  1. Freeze the VHost before restoring master.
  2. Unfreeze the VHost after restoring master.

The following is a general procedure that you can use to restore the master database:

  1. Remote Desktop into the active node that is currently hosting the instance.
  2. Connect DxAdmin.
  3. Right-click on the active node under the VHost and select “Freeze virtual host on node”.
  4. Windows – Open Regedit and browse to the instance key (e.g. HKLM\Software\Microsoft\Microsoft SQL Server\\MSSQLServer\Parameters) and add SQLArg3 with string value of “-m”.
    Linux – Launch mssql-server with the -m parameter (e.g. /opt/mssql/bin/sqlservr -m).
    This puts the instance under single-user startup mode so you can restore master. Restart the instance service to take effect.
  5. Restore master database. See for additional info.
  6. Once master is restored, again using Regedit (Windows only) to remove the single-user startup parameter. Restart the instance service to take effect.
  7. In DxAdmin, right-click on the frozen node under the VHost and select “Unfreeze virtual host” to put the VHost back into normal operation again.