Nagios Support Forum

I'm new to Nagios XI, can I know what is the database that it is running on? What is the recommended space that is required for its directory, for e.g. for demo purposes?
Any documentation on the info that I requested will be helpful.

XI will use MySQL / MariaDB depending on your OS version (Cent/RHEL 6 = mysql, Cent/RHEL 7 = mariadb)

For demo purposes you should be fine with simply 10GB, to be on the safe side you could go with 20GB.