Graceful UPS Shutdowns on Linux - Page 3

 By Carla Schroder
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Network UPS Tools (NUT)
The NUT project supports a wide variety of UPS brands; here is a partial list:

  • APC Smart-UPS, Back-UPS Pro, Matrix-UPS models
  • Belkin Regulator Pro
  • Old Best Power Fortress hardware
  • Energy System
  • ETA UPS hardware with the "PRO" smart mode
  • Fenton Technologies
  • Powerware/Best Power
  • Powercom
  • Tripp Lite

Again, there are nice Debian packages in addition to the usual tarballs; simply install the 'nut' package. NUT is targeted more for network client-server, but it does fine for standalone systems as well. NUT supports mostly serial-port UPS, with a little bit of experimental USB thrown in.

Do not despair if neither NUT nor Apcupsd specifically lists your particular UPS. First, try a driver for similar models; if that doesn't help, NUT has a number of general-purpose drivers that are worth trying. Even though there are many brands, there are a limited number of protocols that are used.

Starting Up After a Shutdown

Usually all you need to make this work is to have it enabled in the system BIOS. (It's usually off by default.) Both NUT and Apcupsd run as daemons, and will start up automatically after bootup.

Smart and Dumb UPS

A $50 UPS isn't going to have all kinds of advanced management circuitry, and it also won't be able to use the many advanced features of Apcupsd and NUT. It will only do two things: switch to battery power when needed and send a signal to the PC that it's time to shutdown. This however is 'Good Enough' for many users — it sure beats the heck of out waking up to confused file systems and fried drives.

Sneaky Cable Gotchas

As usual, some manufacturers think we will be happier customers if they sell us overpriced, non-standard cabling. Make sure your units come with all the necessary cables, and be careful to keep them matched up to the correct devices. (OK, there may be a reasonable technical reason to put custom pinouts in a USB or serial cable. Sure.)


Most UPS are designed so that users can easily replace the batteries. On a standby-type unit, expect 4-6 years of battery life. On a true UPS, I replace them annually, because they are used on very important machines and work harder than normal, but they could probably go longer. Higher-end units have hot-swappable batteries, which is a lovely feature to have when you're looking at annual battery replacements.


Apcupsd home page
NUT home page

» See All Articles by Columnist Carla Schroder

This article was originally published on Jan 7, 2004
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