Here is a way I found to edit rrd files in order to eliminate spikes, inaccurate measurements and other artifacts on my persistence.

To start with, openhab2 has to be stopped:

$ sudo systemctl stop openhab2

Next navigate to your persistence storage folder and locate the rrd files that I wanted to edit. I copied them on a temporary folder:

$ cd /var/lib/openhab2/persistence/rrd4j (or your samba path: \\servername\openHAB-share\openhab2-userdata\persistence\rrd4j)

$ cp -Rpdf Boiler_Temp_Val.rrd /tmp

Next was the RRD File Inspector ( rrd4j-2.1.1.jar_.7z (76 downloads) ).

It is located in the library org.openhab.persistence.rrd4j under the folder /lib/rrd4j-2.1.1.jar

On my machine it is located under the /var/lib/openhab2/tmp/mvn/org/openhab/persistence/org.openhab.persistence.rrd4j/1.11.0/

I extracted the contents of the jar file using a zip extractor (I did this from my windows workstation using 7zip):

To run the inspector I opened a command line (cmd) and run:

java -cp rrd4j-2.1.1.jar org.rrd4j.inspector.RrdInspector

From the RRD File Inspector I opened the files I wanted to edit:

  

I saved files and then placed them back at the openhab persistence folder.

Finally, restarted openhab: $ sudo systemctl start openhab2