[Nut-upsuser] Server not shutting down before power loss

Charles Lepple clepple at gmail.com
Mon Dec 28 22:50:35 UTC 2015

[please use reply-all to include the list. thanks!]

On Dec 28, 2015, at 2:24 PM, Jonah Naylor <jonahnaylor at gmail.com> wrote:
> I have an Ubuntu Server running 14.04.3 LTS and using an APC ES550 UPS connected via USB.
> I've installed Nut and can see it does monitor the UPS correctly and give the correct stats with battery percentage etc.
> But on doing a "real" test and unplugging the UPS from the power supply, after watching the battery drop slowly suddenly the server just lost power along with the UPS and monitor. No graceful shutdown and I didn't see any attempt at a warning or shutdown in any way.

Thank you for sending complete version and hardware information.

A couple of things here:

* APC units seem to be sensitive to proper grounding. While this is more important when calibrating the battery (NUT FAQ #41/42 [1]), you might want to use a power strip or other switch to test in the future.

[1] http://www.networkupstools.org/docs/FAQ.html

* It's safer to use a dummy load (lamp, PC with no hard drives, etc) when testing shutdown scenarios. You will be able to see the UPS turn off power, but it won't harm an important computer.

* If the battery drains from 100% to say, 80%, then cuts out without warning, the UPS needs to recalibrate itself (best done with a dummy load, but there is less risk of cutting power to the computer: the UPS can end the test early and switch to line power by itself) or the battery needs to be replaced (lead acid batteries should be replaced every 3-5 years). Unfortunately, the DDL [2] entry for your UPS doesn't mention which calibration commands are supported, but you can list them with "upscmd -l <name-of-UPS>". If you send the output of that command, plus the output of "upsc" for your UPS, we can update the DDL. Be sure to check the output for serial numbers if you don't want that published online. (The first few digits can be helpful, though.)

[2] http://www.networkupstools.org/ddl/APC/Back-UPS_ES_550.html

Charles Lepple
clepple at gmail

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