Start up automatically after a power failure - APC UPS

Have you checked with the manufacturer?

What about functionality in Snow Leopard which you are using?

My issue is that when I pull the plug on the UPS to test it -

From other discussions here, this is one of the worst tests or ways to see what happens.

Glenn Gerrard wrote:
@hatter - I am open to other ways to test a UPS' uptime on battery power, other than pulling the power from the wall (although it seems like testing a backup, by not doing a restore) - suggestions?

Some say (and some UPS makers used to say) don't test that way, because that disconnects the ground as well as the power, and not necessarily at the same millisecond. The ground might disconnect before the power. They say to shut the power off at your electrical panel by turning-off the breaker. Recent UPS documentation (from APC, anyway) doesn't mention this, so it's questionable whether it's really a problem.

@sigg - the functionality I am after is the at the iMac restarts after it has been gracefully shut down by the UPS tab in the Energy Saver Preferences Pane when the UPS is running on battery power, when power is again supplied via the wall socket. I have checked the box in the Energy Saver preferences pane, but I am not getting the expected outcome

Have you checked that box on +*both versions+* of Energy Saver (Power and UPS)? I've not tested that, so am not sure which one, if either, would apply in that case.

(I don't have mine checked because I'm not sure it's really a good idea for the Mac to power-up when power is restored and the UPS battery is empty or near empty. In the event of a major power loss, when power is first restored, there are often rather extreme spikes and dips as every motor in the area is starting up, especially in A/C units. If the battery is near empty, it might not be able to hold power for long, and the Mac might power down and up repeatedly.)

As a workaround, is there a LAN device on your network that can send the 'magic packet' required for Wake On LAN to invoke your Mac to wake up? This could avoid the need for the UPS to cause the Mac to restart.

Glenn Gerrard wrote:
. . .
I have checked the box on both Power/UPS tabs and tested in all combinations - what is weird is that the machine will restart if goes down hard, but not if it goes down gracefully - I can schedule the machine to start at anytime of the day, so why not after a graceful shutdown + UPS back online? Seems weird to me.

Agreed. Sounds like a bug to me, although it may be something that just wasn't in the original design.

I'd suggest reporting it as a bug, and see what Apple has to say. See: Reporting a Problem to Apple.

Glenn, concerning this comment you made...

My issue is that when I pull the plug on the UPS to test it - the iMac runs for 5 minutes and shuts down gracefully (yay!) however when I plug the UPS back in, the iMac does not restart - I need to press the power button on the iMac OR the UPS.

...what happens if you unplug the Mac from the UPS (while it is in a power off state) and then plug it into the wall? My guess is it will restart.

It seems to me that if the iMac is turning on when the power button on the UPS is pressed, then it sounds like the iMac is primed and in the correct state waiting for power to be restored. Probably what is happening is that the outlets on the UPS never power down unless the battery fully drains. In that case, the Mac does not restart because it doesn't see power being restored since power never stopped being applied. In other words, for the test you are doing, the outlets on the UPS never come back on (because they never turned off).

It still seems to me this could be corrected in the UPS. Can't the UPS be set to toggle it's own power switch in the same way you are manually doing so? That would produce the necessary power interrupt from which the Mac's restart would be keyed.

BSteely wrote:
. . .
It seems to me that if the iMac is turning on when the power button on the UPS is pressed, then it sounds like the iMac is primed and in the correct state waiting for power to be restored. Probably what is happening is that the outlets on the UPS never power down unless the battery fully drains. In that case, the Mac does not restart because it doesn't see power being restored since power never stopped being applied. In other words, for the test you are doing, the outlets on the UPS never come back on (because they never turned off).

That's true, but the UPS does send a signal to the Mac that utility power has been restored, and it's no longer supplying battery power. It appears the Mac is ignoring that signal.

That's true, but the UPS does send a signal to the Mac that utility power has been restored, and it's no longer supplying battery power. It appears the Mac is ignoring that signal.

Wait a minute. How can that be true? How can a Mac that is turned off receive any kind of signal? A "dirty shutdown" puts a Mac into a state where restored AC power will cause it to start up. But other than through that action, there is no other way to get a "signal" into a Mac that is turned off. That's how I understand this to work.

BSteely wrote:

That's true, but the UPS does send a signal to the Mac that utility power has been restored, and it's no longer supplying battery power. It appears the Mac is ignoring that signal.

Wait a minute. How can that be true? How can a Mac that is turned off receive any kind of signal? A "dirty shutdown" puts a Mac into a state where restored AC power will cause it to start up. But other than through that action, there is no other way to get a "signal" into a Mac that is turned off. That's how I understand this to work.

Then why is there a +Start up automatically after a power failure+ option on the UPS tab of System Preferences > Energy Saver? Since the whole point of that entire tab is to do an orderly shutdown, before the UPS battery runs down, what could that option possibly do?

It's either a bug because it doesn't work, or it's a bug because it can't work. Either way, it's a bug.

Then why is there a Start up automatically after a power failure option on the UPS tab of System Preferences > Energy Saver?

So the Mac can start up after a power failure. But if power never left its AC input, how can that be considered a power failure? From the Mac's perspective, there wasn't one.

There needs to be a way for the power outputs of the UPS to toggle once the utility comes back. If that doesn't happen, the Mac won't restart. So that is the simple question to be asking a UPS vendor. Can the UPS's outputs be made to toggle when utility returns. If that can be accomplished, then this problem is solved.

It's either a bug because it doesn't work, or it's a bug because it can't work. Either way, it's a bug.

Maybe. But it hardly seems like it would be confined to a Mac. Are you saying a PC that has been completely shut down can somehow restart under the same conditions? From a signal being issued by a UPS, presumably over a serial port or some other interface? That's a pretty fancy service processor that can accomplish that trick. That doesn't sound like something a normal PC would be able to do.

Glenn, I have a suggestion that is more specific to your case. What is the runtime you get from the UPS that is backing your iMac? You mention the power goes down for 15 minutes. If that is a fairly reliable figure, and if you are getting something like double that or more in runtime from the UPS, why not just hold off on initiating the shutdown sequence of the iMac? Perhaps you can get it to run right through the outage without any need of a shutdown at all. Would that work?