APC UPS shutdown not so clean

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Miataguy2000 Author

Level 1

20 points

APC UPS shutdown not so clean

Running a 2019 iMac with Big Sur plugged in to an APC RS 1500MS2 UPS.

Settings are set to shut down the computer when the UPS battery level is below 25%.

Tested it today.

Sure enough, at roughly 25% UPS battery power remaining, the computer shut down. But it was less than "orderly".

I deliberately left Quickbooks running to see if it would shut down and do an automatic backup, as it does when I shut it down manually. It did not. No backup was created. Same with Quicken. Looking in the logs, I don't see a "SHUTDOWN" entry.

So what's the point of a UPS orderly shutdown if it doesn't do it in an orderly fashion?

(And before anyone asks - the UPS was still supplying power to the other devices I have plugged into it, so I know it didn't run out of power and do a "pull the plug" type of shutdown.)

Is this a bug in Big Sur?

Posted on Sep 5, 2021 11:17 AM

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Answer 1

babowa

Level 9

78,562 points

Sep 5, 2021 11:49 AM in response to Miataguy2000

Does your UPS offer options for an "orderly" shutdown? I don't believe they do unless you install their software, which (I also believe) is not compatible with macs. I've always had to do things manually when I had one (but that might have changed).

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Answer 2

babowa

Level 9

78,562 points

Sep 5, 2021 12:17 PM in response to Miataguy2000

I was not running Big Sur when I had the APC unit and an orderly shutdown was not an option as far as I remember - my UPS never even approached a low battery level. Mine was simply set up to shutdown if there was a power failure and, although we used to have those quite often, my Mac never had any open apps at that point as it always was in the middle of the night.

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Answer 3

Miataguy2000 Author

Level 1

20 points

Sep 5, 2021 11:58 AM in response to babowa

The shutdown is not a direct function of the UPS. Its a function of the MacOS software. The UPS has a cable that plugs into the iMac, and via that cable, it reports to the OS what the battery level is. The orderly shutdown is initiated by the OS based on the info from the UPS. It is absolutely compatible.

In fact, I did a slightly different test yesterday and it did do an orderly shutdown. But today it didn't. The only difference was that yesterday, told it to shut down after 5 minutes on UPS power, and the screensaver had not yet kicked in. So I'm wondering if the behaviour is different based on some other conditions.

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APC UPS shutdown not so clean

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