# Have UPS but system reboots on power loss



## drhowarddrfine (Nov 20, 2020)

I installed 12.0-RELEASE using ZFS from the standard installer just to make sure ZFS works with my motherboard since it's getting somewhat old--maybe six years. I have a UPS attached and I can pull the plug on it and the workstation and all the peripherals stay on for a couple of minutes, at least. However, twice in the last few weeks, I've heard the UPS beep saying we've lost power and, a second later, I hear a boom outside indicating they must have done a power switch or lost a transformer (construction in the area). This power loss is so brief that I don't notice anything like appliance lights going off or clocks resetting and blinking.

But within a second or two, the system powers down and reboots. I don't see anything in the logs indicating any problem. I have wake on lan turned off. To be sure, I unplugged the UPS again and everything keeps humming along normally. 

I have a Gigabyte GA-Z77X-UD5H motherboard. I'd have to look up the power supply manual to see if there is some feature there that might be causing this but I'm looking for hints as to where the problem might lie.


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## SirDice (Nov 20, 2020)

Does it actually power down and back up or does it reset? It's going to be tricky trying to find out what happened as the logs would show the same thing in both situations. 

A lot of mainboards also have an option regarding the power state. I usually set this to "last state". But you can also set this to "always on" or "always off". If it's "always off" it will remain off when the power goes out and comes back again. If it was a reset it would remain powered on.


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## drhowarddrfine (Nov 20, 2020)

I presume it powers down because the power on/off light goes out and I heard the speakers pop. A second or two later, the graphic card fans whir up at high speed and the system reboots.

I'll look at the manual for now to see if there's a "power state" setting.

EDIT: So there is an AC BACK setting about the return of power loss. Also a ErP setting which I'll look into.

I've not had this issue before but I did a factory reset when I made a mistake and I'm betting that changed one of the settings I put there years ago. I'll look into this later when I have a chance.


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## ralphbsz (Nov 20, 2020)

drhowarddrfine said:


> I presume it powers down because the power on/off light goes out and I heard the speakers pop. A second or two later, the graphic card fans whir up at high speed and the system reboots.


My server at home does something like that on a reboot. Type "reboot" at the console, FreeBSD goes down, then the server goes off for a fraction of a section (all lights off, fans off), then comes back on. I was very surprised when I saw that the first time.


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## drhowarddrfine (Nov 20, 2020)

Well, I don't understand why it's rebooting. The AC BACK setting was off. I set it to MEMORY which I thought might be something like SirDice's "last state" setting but that booted into a black screen. I now have it set to ON which might be what I want but I'll have no way of knowing until I get another power glitch like this morning.

Of course, it could be something with the power supply but I don't know how smart it is. That's one manual I don't have on my computer but I'll look for it now.


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## SirDice (Nov 23, 2020)

drhowarddrfine said:


> The AC BACK setting was off.


Then the machine should have stayed off when the power came back on (you have to hit the power button to turn it on). So it's likely a reset not a power down/power up cycle. The reset could be due to a power spike?


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## drhowarddrfine (Nov 23, 2020)

SirDice said:


> The reset could be due to a power spike?


Yes but the UPS should have protected against that. I know they aren't perfect but I've never had this issue before. Not that things don't ever change or get old.


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