So long as you have the DBD driver available and a schema, the code should work with most standard SQL systems.
Schemas are provided in the If there isn't a schema available for your preferred RDBMS, consider creating and contributing one (more info in docs/) Most database backends will require a server, database name, and user credentials.
When an Open VPN server is terminated (or the app/OS crashes) there will be no disconnect event despite a partial database row for the connection.
In order to do partial-updates of status files, you must: You will need to set up some regular process by which the program is told to parse a status file from Open VPN; this could be cron, or some other on-demand event that suits your needs.
This will cause Open VPN to reject the connection when the script is called using the --client-connect Open VPN directive.