Tvheadend

Yes, that's all you need to do. If the IP of your Tvheadend server changes, just be sure to change your clients, too. But backing up the .hts folder is all that's needed.

ok thanks!

is it possible to reinstall tvh and only keep/backup the recordings, e.g. delete all other config?
is there a possibility to reinitialize the recordings?

thanks

The DVR database is a collection of JSON files in .hts/tvheadend/dvr. You should be able to just backup that folder, and be good to go. (If you want to maintain not only a record of what was recorded to prevent duplicates/re-recordings, but also the files themselves, then save your recorded files and make sure they're available from the same filesystem path as they previously were. For example, I store all of my recordings in /media/tv/recorded; when I move my Tvheadend installation to a new machine, I make sure that all of my recordings are accessible from this path, whether it's on the root filesystem, mounted from an external device or other harddrive, or via NFS or SMB, /media/tv/recorded is always the mountpoint for the root of the recordings.)