Not a question but just for information for those interested:
I run HA on a Dell Wyse 5070 mini computer and it works fine.
However, I wanted to create a backup system just to be sure.
I had an old laptop with Windows 10 as a spare.
I have now installed Oracle Virtualbox with HA on it. The HA installation manuals describe very well how to do this.
Also how to use an existing backup to restore on the backup system.
For testing and updates, you do want to activate the backup system from time to time. However, having two HA servers running within the same network at the same time is not possible, as far as I know. However, there is no need to completely shut down your main system. It’s enough to stop the ha core. I do this through a terminal connection using Putty. This does require the installation of the add-on ‘Terminal & SSH’. You can then simply use the commands ‘ha core stop’ and ‘ha core start’ to stop and start the core. This takes less time than a full reboot. In my case, also simpler because the Dell Wyse is not connected to a keyboard and monitor by default and can therefore only be accessed remotely via the network.