MSDN Blogs and One of my post about the same topic with more details https://anoopcnair.com/2012/11/12/configmgr-sccm-how-to-turn-on-verbose-sql-nal-logging/
Debug and Verbose provides additional information on error conditions for clients and servers. Setting this flag automatically triggers more information in the logs and does not require a reboot or restart of the system.
Enabling Debug and Verbose Logging
To enable debug logging after installation, create the following registry key:
To enable verbose logging after installation, change the following value to 0.
(You will need to right click on the @Global key and change permissions to allow the current user to change the data in the key)
You’re done! Log files should now start producing A LOT more information.
32bit Windows Server
64bit Windows Server
Create a new KEY called “DebugLogging” and provide a string value “Enabled” to the default key.