Your question (and response) were pretty much off-topic which is why I moved them (and which is why you didn’t get any answer).
Pay attention to the forum posting rules and open your own thread next time, please.
How to ask a good question / Help Us Help You - Tutorials & Examples - openHAB Community
As your option obviously requires you to take OH down SD mirroring is a better option. It works with an up to date openHABian if you handle it right. Then again this is not what it was built for so the better option would be to properly setup Amanda.
It works fine in current openHABian installs