So that was pretty much a fail. I asked ChatGPT, how I could achieve this with the “other” consolidation. The answer was
a) save the old RRD files
b) rrdtool dump the old files
c) create a new one with other rules
d) rrdtool restore
So (for example) for the rooms metric (of course for all others too) I was doing this:
b) rrdtool dump KMS_Statistics_rooms.rrd > KMS_Statistics_rooms_old.xml
c) rrdtool create KMS_Statistics_rooms.rrd --start 1677393837 --step 60 DS:data_source_name:GAUGE:120:U:U RRA:AVERAGE:0.5:1:525600
d) rrdtool restore KMS_Statistics_rooms_old.xml KMS_Statistics_rooms.rrd
Step d) failed with “file already exists”. Attempting “–force” failed with “parameter not known”. Ok, I was ready go drop the old content, but in fact the GUI spit an error, that there where no “rrd data to create the graph”. In the end I just restored the files from step a) and all was as it was.
Some pointers pretty much appreciated.