Where GeoServer store all users data?

I’m learning how use GeoServer in production. There is a thing that isn’t clear for me: where GeoServer saves all the users data?
I know that there is the data folder inside webapps/geoserver/, I use it, but this is the only one place?
For example there is a Disk Quota settings that give the possibility to use PostgreSQL or Oracle instead of H2 DB. Normally I put this option disabled then I don’t need to use the H2 DB or other type. How GeoServer remembers the association between user and layers? There is a file or a DB?