openHAB3: How to define persistence

I would like to bring this topic up again - especially with an eye on the default persistence service rrd4j.

Based on the above and also some sentences over here: [wiki] Building Pages in the OH3 UI: documentation draft (3/3), the persistence service needs to be configured in a file within the persistence directory.
However I haven’t configured regarding for persistence and I can see some data when selecting the analyze button. Also I recognized the states of some items are restored after a reboot of openhab (this applies just to switch items, but not to text items.)

Now there are two questions coming up.

  1. Is there a default configuration for the default rrd4j persistence service?
  2. If so: Which items (datatypes of items) are stored per default?

I’m currently running OH3 M5.