Graceful UPS Shutdowns on Linux - Page 2

By Carla Schroder | Posted Jan 7, 2004
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Linux-Friendly UPS

Tripp Lite, APC, and Minuteman all provide some Linux software bundles, but not for all of their products. As usual, heroic persons in the Linux world have risen to the occasion to fill in the gaps. Here are a couple of Linux projects that should meet your needs.

Apcupsd
Apcupsd is a great project for APC products. It works best when used with newer APC devices over a USB interface, and when run on newer Linux distributions, although it does also support older, serial-port APC UPS models.

Apcupsd comes in RPMs, source tarballs, and is also in Debian's repositories, so a simple 'apt-get install apcupsd' will fetch and install it.

Some of the so-called Linux drivers supplied by vendors are little more than dumb signal interfaces — all they know to do is how to switch to battery, and then shut the system down after so many minutes, even for UPS units with "smart" capabilities. Or they expect the Linux PCs will be monitored from a Windows server. As if!

Apcupsd, on the other hand, comes with a number of useful system monitors. All of the collected information is displayed on a nice, colorful HTML page, showing the current status for all of your UPS units. Useful information like online status, charge level, load level, and battery run time is displayed on the Apcupsd status page.

Apcupsd also does "slave" shutdowns. When there is more than one PC connected to a UPS, only the "master" PC needs to be connected via the USB or serial cable, and only that computer needs to have the drivers and management software installed. The slave machine runs a monitoring daemon that responds to any shutdown command from the master.

The slave machines can be configured individually; I usually set them to shutdown quickly, to save battery power for the master. (Note: I use "master" and "slave" for consistency with the Apcupsd documentation. You are welcome to call them anything you want.)

You can also turn any networked computer into a slave using NIS. (Obviously this has little utility if the PC is not connected to a UPS.) This lets you use any NIS server as the master.

The Apcupsd site provides a wealth of documentation, including wiring diagrams should you need to make your own cables.

Page 3: Network UPS Tools (NUT)

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