[Nut-upsuser] Confusion on Primary and Secondary

[Scott Ksander]

Thank you much for the great information.  Much appreciated.

Sorry for the PiNUT reference.   This information I used is https://www.jeffgeerling.com/blog/2025/nut-on-my-pi-so-my-servers-dont-die

Thanks again,

Scott

From: Jim Klimov <jimklimov+nut at gmail.com>
Sent: Sunday, March 30, 2025 8:06 AM
To: Scott Ksander <ksander at purdue.edu>
Cc: nut-upsuser at alioth-lists.debian.net
Subject: Re: [Nut-upsuser] Confusion on Primary and Secondary

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Hello and welcome,

  Can you please point to any online "PiNUT" docs, if that is a project name? I did not find anything that looked specific to the key word.

  In any case, the "primary" role of upsmon applies to any UPS that it is connected to and can directly manage, so in case of a power outage it tells everyone else (secondaries) to shut down first, and then runs the UPS driver program in its own shutdown hook to tell the UPS to turn off and power-cycle when power comes back.

  Note that the NUT-protected system can be fed by several UPSes either natively (has many power supply units - PSUs - built in) or through an ATS/STS which is fed from several sources and feeds one PSU of the server. This is where MINSUPPLIES value comes in - how many healthy PSUs are enough for this machine to not worry, and "powervalue" in MONITOR lines for each UPS (how many PSUs of this system that UPS feeds).

  In your case, both "MINSUPPLIES" and the "powervalue" of UPSA in the `upsmon.conf` on the Pi would be 1, and "powervalue" of other UPSes would be 0 (monitored only for curiosity/logging/...) while it is still a "primary" for all 3 (can tell others about FSD).

Hope this helps,
Jim Klimov


On Sun, Mar 30, 2025 at 1:07 PM Scott Ksander via Nut-upsuser <nut-upsuser at alioth-lists.debian.net<mailto:nut-upsuser at alioth-lists.debian.net>> wrote:
I have a PiNUT setup.  It is physically connected (USB) and monitoring 3 UPS units (UPSA, UPSB, and UPSC).   The PiNUT is powered by USPA.   UPSA powers other equipment with clients installed.   Other equipment will be clients of UPSB and UPSC.

I am confused about how to correctly configure the PiNUT settings.  I have searched for howto notes but they seem to have conflicting information.  Should all 3 connections (USB)  be primary?  Do I increment the powervalue in the MONITOR directive or should all show 1?

Thanks for any pointers,

Scott
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