Finding the  SQL Server default data and log location  (or Database default Locations ) is useful. When a CREATE DATABASE command is issued with target location paths explicitly stated , SQL Server will  create the data and log files in the default data and log locations.

That’s not always the intended result.   For example, the DBA may need to change the location of system files or move all databases due to disk issues or to improve database performance - read more on  SQL Server – files and filegroups. Improving database performance

Method 1 : Use SSMS to view Default Data and Log details

1. In the SSMS Object Explorer panel, right-click a server and click
2. Properties.
3. In the left panel,under Select A Page title,  click the Database settings page.
4. In Database default locations, view the current default locations for new data files and new log files.

 Method 2: T-SQL and xp_instance_regread

DECLARE @DataLoc nvarchar(2000);
DECLARE @LogLoc nvarchar(2000);

EXEC master.dbo.xp_instance_regread
    N'HKEY_LOCAL_MACHINE',
    N'Software\Microsoft\MSSQLServer\MSSQLServer',
    N'DefaultData', 
    @DataLoc OUTPUT;

EXEC master.dbo.xp_instance_regread
    N'HKEY_LOCAL_MACHINE',
    N'Software\Microsoft\MSSQLServer\MSSQLServer',
    N'DefaultLog', 
    @LogLoc OUTPUT;

SELECT @DataLoc AS 'Default Data Location',
       @LogLoc AS 'Default Log Location';

 Read More

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