rrd4j persistence is now enabled by default to make it easy for newbies. The default strategy is to persist on every change and once a minute. There is no rrd4j.persist file though.
Any advice on the best way to migrate my historical persistence data from OH2 to OH3? Evidently I could just copy the .persist file over. But it would be far nicer to be able to import the file contents into whatever new storage format that OH3 uses.
.persist files are the last remaining core text config for which there is no way to do through the UI. So you can keep the default strategy or you have to create a .persist file.
If you mean the data itself, the .rrd files are in userdata/persistence/rrd4j - if you copy them over to the same location, and have the same item names and strategies, it might just work.
Ok I understand that. But I am also interested in how the rrd4j.cfg file is handled in future; in my case I use the default archiving form AVERAGE for most items, but for certain items I use MAX resp. 'MIN` …