It’s never an issue to open a new thread as long as the question is relevant to OH2
Back to your problem, see:
YOUR data is in /var/lib/influxdb/data
The wal directory is used by influx to manage incoming data and grows until a certain size is reached and then compressed and archived.
Yes
See link above
Because that folder contains data, wal and meta. As wal grows, so does the parent directory.
I highly recommend that you use an SSD and USB port
You SD card WILL FAIL
You can boot from the SD card and move everything else to the SSD.
I believe that openHABian has an option to do that
well, I guess I can move openhabian to an USB stick as you said. And for the other Raspberry that I use for my Cloud and to store data of influx, I might use an SSD.
It is recommended to have Influx running in other system different than openhab one.
I didn’t say USB stick, I said SSD. A USB stick uses the same technology as an SD card (An SSD too by the way but it has protection buffers) and the stick will fail eventually too.
I use good old fashioned hard drives for storage, swapping and logging. I use SSD for the OS and I try to minimize the writes on it.