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I have used apcupsd under ubuntu to power off my machine when AC power is lost via serial.

Is there any way let the UPS to wake up already powered off machine when AC power is back? I have tried to enabled everything in BIOS that corresponding to wake up by ring, still no luck.

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migrated from Apr 26 '11 at 12:06

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You would normally use a network enabled PDU and connect to a network enabled UPS. – Steve-o Sep 9 '11 at 8:23

This should be a standard feature of BIOS, and handled easily by apcupsd.

You are looking in BIOS for power-auto-return, power-return, OR after-power-loss. This can be enabled, disabled, or (for more recent BIOS) last-state. The 'last-state' option means: did you manually leave the machine on OR off, using the power switch.

I have used an APC UPS, with apcupsd and USB connection, to do precisely what you are trying to do.

The UPS givith and the UPS taketh away. (but in reverse):

When the UPS is low on battery, it halts power to the machine. When it again has mains-power, it returns power to the machine. From the machines viewpoint, the power was removed and restored, BUT outside its control. It should just follow the BIOS setting for: 'after power loss".

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I apologize for what may be a complex answer.

I think the issue would be that the computer is receiving power from the UPS until it runs out of battery... thus when power comes back on there is no 'change in state'. If the UPS were to have run out of power I believe the server settings for automatically power on would work. If you have a way to send a magic packet then wake on lan might work.

see link:

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You could use an ALIX box with NanoBSD (or pfSense) to connect to a UPS via serial and then have it send a WoL packet. This would avoid requiring a rather expensive investment in a network UPS. – Steve-o Sep 9 '11 at 8:18
+1 for WOL - that's what I would suggest. – Nathan Osman Sep 20 '11 at 16:13

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