Database Engine Service Startup Options

APPLIES TO: yesSQL Server noAzure SQL Database noAzure Synapse Analytics (SQL DW) noParallel Data Warehouse

Startup options designate certain file locations needed during startup, and specify some server wide conditions. Most users do not need to specify startup options unless you are troubleshooting the Database Engine or you have an unusual problem and are directed to use a startup option by SQL Server Customer Support.

Warning

Improper use of startup options can affect server performance and can prevent SQL Server from starting.

Start SQL Server on Linux with the "mssql" user to prevent future startup issues. Example: sudo -u mssql /opt/mssql/bin/sqlservr [STARTUP OPTIONS]

About Startup Options

When you install SQL Server, Setup writes a set of default startup options in the Microsoft Windows registry. You can use these startup options to specify an alternate master database file, master database log file, or error log file. If the Database Engine cannot locate the necessary files, SQL Server will not start.

Startup options can be set by using SQL Server Configuration Manager. For information, see Configure Server Startup Options (SQL Server Configuration Manager).

List of Startup Options

Default startup options

Options Description
-d master_file_path Is the fully qualified path for the master database file (typically, C:\Program Files\Microsoft SQL Server\MSSQL.n\MSSQL\Data\master.mdf). If you do not provide this option, the existing registry parameters are used.
-e error_log_path Is the fully qualified path for the error log file (typically, C:\Program Files\Microsoft SQL Server\MSSQL.n\MSSQL\LOG\ERRORLOG). If you do not provide this option, the existing registry parameters are used.
-l master_log_path Is the fully qualified path for the master database log file (typically C:\Program Files\Microsoft SQL Server\MSSQL.n\MSSQL\Data\mastlog.ldf). If you do not specify this option, the existing registry parameters are used.

Other startup options

Options Description
-c Shortens startup time when starting SQL Server from the command prompt. Typically, the SQL Server Database Engine starts as a service by calling the Service Control Manager. Because the SQL Server Database Engine does not start as a service when starting from the command prompt, use -c to skip this step.
-f Starts an instance of SQL Server with minimal configuration. This is useful if the setting of a configuration value (for example, over-committing memory) has prevented the server from starting. Starting SQL Server in minimal configuration mode places SQL Server in single-user mode. For more information, see the description for -m that follows.
-kDecimalNumber This startup parameter limits the number of checkpoint I/O requests per second, where the DecimalNumber represents the checkpoint speed in MB per second. Changing this value can impact the speed of taking backups, or going through the recovery process so proceed with caution. For more information about this startup parameter, please see hot fix where the -k parameter was introduced.
-m Starts an instance of SQL Server in single-user mode. When you start an instance of SQL Server in single-user mode, only a single user can connect, and the CHECKPOINT process is not started. CHECKPOINT guarantees that completed transactions are regularly written from the disk cache to the database device. (Typically, this option is used if you experience problems with system databases that should be repaired.) Enables the sp_configure allow updates option. By default, allow updates is disabled. Starting SQL Server in single-user mode enables any member of the computer's local Administrators group to connect to the instance of SQL Server as a member of the sysadmin fixed server role. For more information, see Connect to SQL Server When System Administrators Are Locked Out. For more information about single-user mode, see Start SQL Server in Single-User Mode.
-mClient Application Name Limits the connections to a specified client application. For example, -mSQLCMD limits connections to a single connection and that connection must identify itself as the SQLCMD client program. Use this option when you are starting SQL Server in single-user mode and an unknown client application is taking the only available connection. Use "Microsoft SQL Server Management Studio - Query" to connect with the SSMS Query Editor. The SSMS Query Editor option cannot be configured by using SQL Server Configuration Manager because it includes the dash character which is rejected by the tool.

Client Application Name is case sensitive. Double quotes are required if the application name contains spaces or special characters.

Examples when starting from the command line:

C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Binn\sqlservr -s MSSQLSERVER -m"Microsoft SQL Server Management Studio - Query"

C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Binn\sqlservr -s MSSQLSERVER -mSQLCMD

Security Note: Do not use this option as a security feature. The client application provides the client application name, and can provide a false name as part of the connection string.
-n Does not use the Windows application log to record SQL Server events. If you start an instance of SQL Server with -n, we recommend that you also use the -e startup option. Otherwise, SQL Server events are not logged.
-s Allows you to start a named instance of SQL Server. Without the -s parameter set, the default instance will try to start. You must switch to the appropriate BINN directory for the instance at a command prompt before starting sqlservr.exe. For example, if Instance1 were to use \mssql$Instance1 for its binaries, the user must be in the \mssql$Instance1\binn directory to start sqlservr.exe -s instance1.
-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, see Trace Flags (Transact-SQL).

Important: When specifying a trace flag with the -T option, use an uppercase "T" to pass the trace flag number. A lowercase "t" is accepted by SQL Server, but this sets other internal trace flags that are required only by SQL Server support engineers. (Parameters specified in the Control Panel startup window are not read.)
-x Disables the following monitoring features:
- SQL Server performance monitor counters
- Keeping CPU time and cache-hit ratio statistics
- Collecting information for the DBCC SQLPERF command
- Collecting information for some dynamic management views
- Many extended-events event points

Warning: When you use the -x startup option, the information that is available for you to diagnose performance and functional problems with SQL Server is greatly reduced.
-E Increases the number of extents that are allocated for each file in a filegroup. This option may be helpful for data warehouse applications that have a limited number of users running index or data scans. It should not be used in other applications because it might adversely affect performance. This option is not supported in 32-bit releases of SQL Server.

Using Startup Options for Troubleshooting

Some startup options, such as single-user mode and minimal configuration mode, are principally used during troubleshooting. Starting the server for troubleshooting with the -m or -f options is easiest at the command line, while manually starting sqlservr.exe.

Note

When SQL Server is started by using net start, startup options use a slash (/) instead of a hyphen (-).

Using Startup Options During Normal Operations

You may want to use some startup options every time you start SQL Server. These options, such as starting with a trace flag, are most easily done by configuring the startup parameters by using SQL Server Configuration Manager. These tool saves the startup options as registry keys, enabling SQL Server to always start with the startup options.

Compatibility Support

For options that have been removed from previous releases, see sqlservr Application.

Configure the scan for startup procs Server Configuration Option
Start, Stop, Pause, Resume, Restart the Database Engine, SQL Server Agent, or SQL Server Browser Service Configure Server Startup Options (SQL Server Configuration Manager)

See Also

CHECKPOINT (Transact-SQL)
sqlservr Application