Today the area where I live experienced what turned out to be an extended power outage, and I wound up going in to the office. In the process, I wound up shooting myself in the foot as far as my ability to tell from the office if power had returned to home, oddly because I have a UPS at home.

The easy way to use a UPS is just to let it run down until it powers off. But this is kind of abrupt on the computer, even if you've more or less halted it already, and it also means that the computer's load reduces the run time for everything else. In my case this matters a bit because after a power loss, my phone line is typically slow to get DSL signal and sync up, so that I can start doing PPPoE and bring up my Internet connection. So if it looks like the UPS's power is running low, my reflex is to power off the computer and hope that power will come back before the UPS bottoms out and the DSL modem turns off (and thus loses line sync).

The first problem is that this only really works if I'm going to stick around to turn the computer on should the power outage end early enough (before the UPS loses power). That turned out not to be a problem this time; the power outage lasted more than long enough to run the UPS out of power, even with only the minor load of the DSL modem, a five-port switch, and a few other small things. The bigger problem is that because of how I have my computer set up right now due to hardware reasons, if I want the computer to be drawing no power (as opposed to being 'off' in some sense), I have to turn the computer off using the hard power switch on the PSU. Once I've flipped this switch, the computer is off until I flip it back, and if I flip it back with (UPS) power available, the computer will power back up again and start drawing power and all that.

(My BIOS is set to 'always power up when AC power is restored', and apparently one side effect of this is that the chassis fans and so on keep spinning even when the system is 'powered off' from Linux.)

The magic UPS feature I would like to fix this is a one-shot push button switch for every outlet that temporarily switches the outlet to 'wait until AC power returns to give this outlet any power'. With this, I could run 'poweroff' on my computer, then push the button to cut power and have it come back when Toronto Hydro restored service. I believe it might be possible to do this with commands to the UPS, but that mostly doesn't help me since the host that would issue those commands is the one I'm running 'poweroff' on.

(The better solution would be a BIOS and hardware that turns everything off after 'poweroff' even when set to always power up after AC comes back. Possibly this is fixed in a later BIOS revision than I have.)