I have got two Ubuntu servers running off a single UPS (APC350). The master server is connected via USB and the slave communicates over Ethernet polling the UPS every 10 seconds or so. I have set up apcupsd such that when the order to shutdown comes to one, the other will shutdown too.
However since the computers are connected via a wired switchbox, I am slightly confused about what will happen in the event of power loss. Since the switchbox will lose power, communication between the servers will be lost, and the server won't know the status of the UPS. How will it know what to do?