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Date:      Tue, 4 Sep 2018 09:47:50 -0500
From:      Valeri Galtsev <galtsev@kicp.uchicago.edu>
To:        Daniel Feenberg <feenberg@nber.org>
Cc:        Chris Gordon <freebsd@theory14.net>, C Gray <frankfenderbender@council124.org>, FreeBSD <freebsd-questions@freebsd.org>
Subject:   Re: APC UPS BackUPS Pro (BX1500M)
Message-ID:  <69d5da40-b66e-a962-5946-052f87b7897c@kicp.uchicago.edu>
In-Reply-To: <alpine.LRH.2.21.1809040931270.2490@sas1.nber.org>
References:  <SN1PR20MB2109533F42733E6EDDAA9616800C0@SN1PR20MB2109.namprd20.prod.outlook.com> <9B877978-297C-499C-86CE-99B68B570245@council124.org> <92A53B5A-BEC2-4A8C-828F-0AD180E30BD0@theory14.net> <59593.108.68.162.197.1536028420.squirrel@cosmo.uchicago.edu> <alpine.LRH.2.21.1809040931270.2490@sas1.nber.org>

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On 9/4/18 8:34 AM, Daniel Feenberg wrote:
> 
> 
> On Mon, 3 Sep 2018, Valeri Galtsev wrote:
> 
>>
>> To solve this last trouble I configure since forever in BIOS power ON
>> after AC power is returned. Usually if UPS has drained battery, after
>> power returns, it powers itself ON, provides power to outputs and starts
>> charging battery. We had this situation once, outage longer that UPS's on
> 
> What happens if power returns during the shutdown sequence? The power 
> never goes off, therefore never turns on, and the computer remains off. 
> Is there a solution other than remote control?

You are absolutely right. So, as far as I remember apcupsd will try to 
abort shutdown, and if the machine didn't go too far in shutdown 
sequence, all will stay. Someone who read apcupsd more recently that I 
did, please, correct me if I'm wrong here. Incidentally, if on battery 
run is 20 min and shutdown starts 2 min before battery drained, the 
chance of outage to be exactly that long is at least 10 times smaller 
that outage shorter than that. But, exactly as you said, the machine may 
get shut down, and stay if outage duration in in that narrow range.

Now, if this happens, you deal with the situation from external box. 
This is the case when you need more important machine that is behind UPS 
with much longer on battery run time. And if you run something like 
nagios (or other host/service watch system), that box can send WOL (Wake 
On LAN) signal some 5 min after it notices that machine is off line. Now 
you have really robust system.

I hope, this helps.

Valeri

> 
> Daniel Feenberg
> NBER

-- 
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++



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