Short question: I noticed the amazing history charts in the new OH3 Web UI, really awesome! Apparently, OH3 uses some kind of preconfigured persistence, but unfortunately, item states are only persisted for ~2 months. Where is the toggle to remove this limitation and save item states forever without deleting them at any time?
Thanks in advance!
There is no limit so there is no setting.
OH3 uses what ever is your default persistence engine (as configured in the settings) as the source for the data for charts.
On a stock installation it will have rrd4j as the database and set that to the default.
In all likelihood that Item simply does not have any information stored before that point. Or you did some modifications to the default persistence data at that point in time. Or you lost the contents of /var/lib/openhab/persistence/rrd4j at that point.
Thanks for the reply, @rlkoshak. Interestingly, all my persistence data are not older than about two months, but my raspi installation is already twice as old, so I wonder how I could lose the prior persistence data. Nevertheless, I will observe whether the current data will disappear as well or will be kept. 
