[Back-UPS 550] How to restart Ubuntu on power loss, after after soft shutdown via 'apcupsd'?

[Anonymous user]

Hello APC-

I've searched the forums, and scoured the internet, without resolution to this issue. I'm running Ubuntu 15.10 (formerly 14) on an Intel NUC (5i), connected to a Back-UPS 550 via USB cable, and can confirm the following:

• apcupsd is installed and working
• BIOS has been set to "Always Resume" in the Power Loss setting
• Basic configuration file exists and appears correct
• Restart-on-power functionality works correctly when not using the UPS -- if I pull the plug on the NUC and then reconnect, the unit powers on.

Shutdown appears to be working correctly in my tests when I pull the plug on the UPS, unfortunately the unit stays off when power is restored.

It's as if the apcupsd shutdown behavior is causing a normal shutdown in Ubuntu, instead of indicating to the hardware that an emergency shutdown took place -- when power is restored to the UPS, the NUC doesn't immediately power-on like it does when not using the ups.

What am I missing here? I've covered a lot of ground online, including: https://help.ubuntu.com/community/apcupsd

Any help is appreciated, and thanks in advance,

[voidstar_apc]

From context, "the unit" is your Intel NUC? Just asking because you could be referring to the UPS.

Check if the UPS itself powers back on after power returns. If so, you need to adjust the NUC's BIOS settings so it will turn the NUC back on. I found a list of NUC BIOS settings:

http://download.intel.com/support/motherboards/desktop/sb/biosglossary_nuc_v05.pdf

From your description, my guess would be that "After Power Failure" is set to "Last State" rather than "Power On".

[Anonymous user]

Hello Voidstar -

Thanks for the reponse, its appreciated.  I've cleared up the post a bit, I was indeed referring to the NUC.

Interesting that you mention the BIOS, I tried this very thing earlier today and did some tests with the power-on-fail set to ALWAYS (it had been set to LAST)

Strangely, I get the same results -- without the UPS, the NUC indeed turns on automaticaly when power is restored after a failure.  However with the UPS connected, cutting the power results in apcupsd initiating a successful shutdown...  Unfortunately once power is restored to the UPS (which appears to be working flawlessly), the NUC just sits there.   Of course if I physically press the ON button the NUC is happy to oblige.

Could it be because the NUC never totally loses power, with the UPS sustaining a live current via battery (after shutdown)?  If so, can the BIOS discern between battery/AC on the UPS, or can it somehow be signalled to simulate a fail/restore?   This scenario would be a kind of catch-22...  Obviously I'd like to take everything offlline prior to a total power loss, but need things to spin back up even if the UPS does its job maintaining current.

If this is the case, then if any shutdown action is taken, the question is how to recover if UPS power isn't lost in full, prior to restoration of line AC...

[voidstar_apc · Accepted solution]

You make a good point -- not only do you need to make sure the UPS is providing power when power returns (even if the NUC isn't turning itself on), but also the UPS needs to turn off the power. That would be a good thing to check, say, with a lightbulb plugged into the same UPS.

The way things are supposed to work is once the monitoring software (say, apcupsd or our own PowerChute) determines it will shut down the system, it also sends a delayed shutdown (wait N seconds, turn off, turn back on when AC is good) command to the UPS. I believe the apcupsd folks call this "killpower". Once the UPS recieves that command, it will shut down even if power comes back before the computer finishes the shutdown sequence. If apcupsd is commanding the computer to shutdown without sending a shutdown signal to the UPS, you'd have a problem. I believe killpower is tucked into one of the shutdown scripts.