Restore the master database (Transact-SQL)
Applies to: SQL Server
This article explains how to restore the
master database from a full database backup.
In the event of disaster recovery, the instance where the
master database is being restored to should be as close to an exact match to the original as possible. At a minimum, this recovery instance should be the same version, edition, and patch level, and it should have the same selection of features and the same external configuration (hostname, cluster membership, and so on) as the original instance. Doing otherwise might result in undefined SQL Server instance behavior, with inconsistent feature support, and is not guaranteed to be viable.
To restore the
Start the server instance in single-user mode.
You can start SQL Server by either using the
-fstartup parameters. For more information about startup parameters, see Database Engine Service Startup Options.
From a command prompt, run the following commands, and make sure you replace
MSSQLXX.instancewith the appropriate folder name:
cd C:\Program Files\Microsoft SQL Server\MSSQLXX.instance\MSSQL\Binn sqlservr -c -f -s <instance> -mSQLCMD
-mSQLCMDparameter ensures that only sqlcmd can connect to SQL Server.
- For a default instance name, use
-cstarts SQL Server as an application to bypass Service Control Manager to shorten startup time
If the SQL Server instance can't start due to a damaged
masterdatabase, you must rebuild the system databases first. For more information, see Rebuild system databases.
Connect to SQL Server using SQLCMD from another Command Prompt window
SQLCMD -S <instance> -E -d master
To restore a full database backup of master, use the following RESTORE DATABASETransact-SQL statement:
RESTORE DATABASE master FROM <backup_device> WITH REPLACE
The REPLACE option instructs SQL Server to restore the specified database even when a database of the same name already exists. The existing database, if any, is deleted. In single-user mode, we recommend that you enter the RESTORE DATABASE statement in the sqlcmd utility. For more information, see Use the sqlcmd Utility.
After master is restored, the instance of SQL Server shuts down and terminates the sqlcmd process. Before you restart the server instance, remove the single-user startup parameter. For more information, see Configure Server Startup Options (SQL Server Configuration Manager).
Restart the server instance normally as a service, without using any startup parameters.
Continue other recovery steps such as restoring other databases, attaching databases, and correcting user mismatches.
The following example restores the
master database on the default server instance. The example assumes that the server instance is already running in single-user mode. The example starts
sqlcmd and executes a
RESTORE DATABASE statement that restores a full database backup of
master from a disk device:
For a named instance, the sqlcmd command must specify the -S<ComputerName>\<InstanceName> option.
C:\> sqlcmd 1> RESTORE DATABASE master FROM DISK = 'Z:\SQLServerBackups\master.bak' WITH REPLACE; 2> GO
Complete Database Restores (Simple Recovery Model)
Complete Database Restores (Full Recovery Model)
Troubleshoot Orphaned Users (SQL Server)
Database Detach and Attach (SQL Server)
Rebuild System Databases
Database Engine Service Startup Options
SQL Server Configuration Manager
Back Up and Restore of System Databases (SQL Server)