Bill Arlofski's blog

Monitoring and Graphing Your UPS Data With NUT & Xymon

For several years now, we have been installing the open-source program NUT (Network UPS Tools) to monitor our UPSes and our clients UPSes to safely shut down servers during extended power outages.

With NUT we can rest assured that servers will not just have their power killed when their UPS's battery dies, but instead will be told to perform an orderly shutdown before the battery is exhausted which can prevent costly issues including file corruption.

The "N" in NUT stands for NETWORK which of course means that there is a networking aspect to it. Not only is NUT capable of monitoring UPSes via serial ports and USB ports but also via SNMP when a UPS supports it.

In addition, the networking capabilities of NUT include the ability for a NUT server to monitor a UPS and tell multiple client machines that also derive their power from the monitored UPS to shutdown prior to the NUT server itself being shut down.

Isn't this enough monitoring? Well, we always say, "...just like backups you can never have too much monitoring." So we have written several scripts for the Xymon Monitoring Server to monitor, graph and alert on the AC input voltage, AC output voltage, battery charge %, battery voltage & UPS load % of UPSes managed by a NUT server.

The scripts and the instructions on how to install and configure them with a Xymon server may be found HERE.

posted from my Nokia N900

Monitoring Your Bacula Backups With Xymon

In a recent post to the Bacula mailing list, someone had asked if there was a way to alert their Nagios network monitoring server when their Bacula backup server was waiting on an operator to change a tape.

At Reverse Polarity, we have been installing and supporting Xymon for years - as far back as when it began as plug-in to the "Big Brother" network monitoring server.

Xymon is an open-source network monitoring program with an easy to use web interface. Since someone was asking about a Nagios plugin to monitor their Bacula server it only seemed logical that someone might want a way to monitor Bacula with a Xymon server.

As it turns out, someone DID want a Xymon monitor for Bacula - Us!

As luck would have it we had already written a Xymon script to monitor our Bacula server and alert if a backup job had failed. All our script needed was some minor additional features and some finishing touches for it to be ready to be released for others to use.

I am excited to say that the script, which is available HERE was announced on the Bacula users mailing list and the Xymon users mailing list on June 4th, 2010 and within 10 minutes was being downloaded and implemented by others!

posted from my Nokia N900

If a device has relays we should control them!

Last week I wrote about monitoring, logging, graphing and alerting on a ControlByWeb temperature module's readings. What I left out was that the module in question also has two relays.

And, if a device has relays, we should do something with them!

Since Xymon is our monitoring solution of choice I wrote a bash shell script that may be called as an alert script for Xymon to turn on, off, pulse or toggle a relay for a specific alert.

Take a look at to see how a Xymon monitoring server can be configured to control a ControlByWeb module's relays.

posted from my Nokia N900

Monitoring Temperature with Open-Source Software

Recently, while looking for a reasonably priced temperature sensor device that we could integrate into a Xymon monitoring server to monitor our server room as well as our clients' server rooms, a Google search turned up and their 4-sensor/2-relay temperature module. It met all of our requirements.

This monitor is not only inexpensive, but it is also very simple to set up. And since the temperature readings are readily available to a web browser, it is just as easy to integrate into a Xymon monitoring server using some simple shell scripting and a great utility called "curl" to pull the state.xml web page that contains the temperature readings.

Take a look at to see the Xymon integration instructions and the actual bash shell script you may use to monitor, log, and graph up to four temperature reading from one of these devices.

To learn more about Xymon and some of the other Open-Source tools we use and support on our network and our clients' networks, see our System Monitoring page .

posted from my Nokia N900