Eight servers have vanished, and three UPSes. Wow. So I looked into it.
The eight servers were easy; there was a loose cable between the power distribution unit (PDU) and the server that interrogated it. As soon as I pushed the cable in firmly, the eight missing servers reappeared.
The UPSes were more difficult. I have three NCR UPSes. They aren't as large and unliftable as the APS units that I mostly use, and they have an ethernet connection so that I can interrogate them and find out how much current they are passing. But during the last power cut, several weeks ago, everything went dark. When power was restored, everything went live again, but the three UPSes get their IP address from DHCP, and when they came up, they had different IP addresses.
So I had to find out their new IP addresses.
To do this, I used nmap, which scans all the ports of a range of IP addresses. That came back with three devices with the name "Viking Modular Solutions". Those were my UPSes; So I told my program that does the interrogations, these IP addresses, and everything worked fine.
I do like these UPSes. I like the way I can remotely monitor them, and I like the fact that at 37 kg, I don't put my back out trying to move them (the APCs are 57kg). The ones I buy a missing the pretty front panel. I don't care.
The four PDU are showing 2.1, 1.7, 2.2 and 0.3 amps. The three NCRs are showing 4.9 amps, 2.4 and 2.3. The 4.6 amps is for my workstation office, which is for four computers, a laptop, three screens and a few bits and bobs. The UPS will give me 15 minutes, so if I have a longish power cut, first thing to do is power down all the computers except one.