Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
Applies to: 
SQL Server on Windows
Use this dialog box to add or remove startup parameters for the Database Engine. Startup parameters can have a large effect on the Database Engine performance. Before adding or changing startup parameters, see Database Engine Service startup options.
Options
Specify a startup parameter
To add a parameter, type the parameter, and then select Add.
To modify one of the required parameters, select the parameter in the Existing parameters box, change the values in the Specify a startup parameter box, and then select Update.
Existing parameters
To remove a parameter, select a parameter, and then select Remove.
Parameter format
Don't enter a separator between parameters. SQL Server Configuration Manager automatically adds the separator. SQL Server Configuration Manager enforces the following parameter requirements.
Leading and trailing spaces are trimmed from any startup parameter.
All startup parameters start with a hyphen (
-), and the second value is a letter.
Required parameters
The following parameters are required. They can be changed but not removed.
-dis the path of themaster.mdffile (themasterdatabase data file).-lis the path of themaster.ldffile (themasterdatabase log file).-eis the path of the SQL Server error log files.
If the file path parameters are incorrect, SQL Server might not start.
For more information about how to move the master database, see Move system databases.
Optional parameters
All of the supported startup parameters are described in Database Engine Service startup options. A startup parameter of -T<trace#> indicates that an instance of SQL Server should be started with a specified trace flag (<trace#>) in effect. Trace flags are used to start the server with nonstandard behavior. For more information about trace flags, see Set trace flags with DBCC TRACEON.
Caution
You might see additional undocumented startup parameters and trace flags described online. Undocumented startup parameters and trace flags are created to address uncommon problems or to force certain conditions required for testing. Using undocumented startup parameters can have unexpected results. Don't use undocumented parameters unless directed by Microsoft Customer Support Services.
The following list describes some common optional parameters.
| Parameter | Short description | More information |
|---|---|---|
-m |
Starts an instance of SQL Server in single-user mode. | Single-user mode for SQL Server |
-T1204 |
Returns the resources and types of locks participating in a deadlock and also the current command affected. | Trace flag 1204 |
-T1224 |
Disables lock escalation based on the number of locks. SQL Server 2025 (17.x) introduces Optimized locking instead. |
Trace flag 1224 |
-T3608 |
Prevents SQL Server from automatically starting and recovering any database except the master database. |
Trace flag 3608 |
-T7806 |
Enables a dedicated administrator connection (DAC) on SQL Server Express. | Trace flag 7806 |
Caution
Some optional parameters can change server behavior and might affect performance.
Permissions
Use of this page is restricted to users who can change the related entries in the registry. This includes the following users:
Members of the local administrators group.
The domain account that is used by SQL Server, if the Database Engine is configured to run under a domain account.