Dear all, i want to try grafana for aome advanced graphs and tables.
I am running openhabian on a RPI 3b+ and openhab 3.4.2.
I found alot old openhab 2 + grafana tutorials but not really something for openhab 3.
I am using the standard RRD4j for logging item values. I really like the fact that the item values are logged when i define them as point or measurement in the openhab UI. Do i really have to use InfluxDB? Do i have to deactivate RRD4j then? What happens to my logged values from the last years? Really dont want lose them… Or can i use both methods parallel and only add the items i want to analyse with grafana in influxdb?
Do i really have to manually add the items i want to log in a text file or can i add them in the UI like using RRD4j?
A lot of newby question…sorry.
Maybe someone can help 
Thank you
Yes, this is your solution. Persistence services can each be enabled and configured individually. You can leave RRD4j as the default service and then setup a persistence configuration for InfluxDB that tracks only certain items using persistence files:
In OH3 any specialized, non-default, persistence will need to be configured via text file. There is, I believe, work being done right now on adding UI persistence configuration to OH4, but that’s not quite ready to go yet.
If you keep RRD4j as your default service then that data will all be preserved. There is no good automatic way to transfer the historical data over to a new service. It’s worth noting, however, that because of the nature of RRD4j storage, your historical data in that format is greatly reduced in temporal resolution anyway. Your influx data will be starting over from scratch.
Influx is just one of the more popular formats, but there are several other DBs that can also be configured for reliable historical data. You just need something more complete than RRD4j to get the most out of Grafana.
Thank you alot for your answer! So i will set up influxdb as an additional service and leave RRD4j as default.