Howto: APC UPS and Debian

So, I have a couple of NAS boxes and a laptop as server running at home. It’s all good until thunder appears. There are multiple risks with this. If the lightning strikes it can cause large surges of electricity that will destroy your equipment, if a power loss occurs it can cause the two RAID5 setups to die and it will cause major data loss.

A couple of days ago I bought a UPS and set it up and now I figured I should also set it up. So I did some reading and this is my result served to make it easier for you.

In this guide, this setup is used:
– Computer with GNU/Linux Debian Lenny
–  APC Back-UPS 800

The software I use is apcupsd which is in the Debian repository. Start by installing it:

apt-get update && apt-get install -y apcupsd

The next thing is to configure it. I did a whole lot of reading the manual for apcupsd to make sure I did things right. When your UPS is set up, hook the USB cable into your server.

Go to /etc/apcupsd and edit the file apcupsd.conf

My UPS and most of the newer UPS’es form APC uses USB to interface with the server, and that makes it easier for us to talk to it. These are the parameters I have set:


Define that we use a USB connection to the UPS.


Set the type to usb and leave the DEVICE property empty. By that it will find out where it is located by itself, and since we use USB it can do that.
These three you should set to fit your needs. How generous you can be really depends on the amount of power you have versus the amount of power you use. My setup uses up around 85 watts, and since I have 800 VA I can keep it running for quite a while. On the product page for your UPS (if it is a APC) you will find a graph that tells you how long you can have it running depending on how much power you use. If you do not have any idea whatsoever about your power usage, you should get an energy meter and measure it first. If you have an idea, buy an appropriate UPS and set the levels as above. Later I will test the communication to the UPS and that will tell you how long it can keep you running – which also means you will know how to set your thresholds.
Now, these were all the customizations I did to the config file. Edit the file /etc/default/apcupsd:
If you do not do this, it will refuse to start. Next, start it:
/etc/init.d/apcupsd start
Now, you can issue the command “apcaccess” and it will talk to the UPS and show you some information. You should see something similar to this (and more)
# apcaccess
APC      : 001,044,1076
DATE     : Thu Nov 25 10:20:32 CET 2010
HOSTNAME : natalie
RELEASE  : 3.14.4
VERSION  : 3.14.4 (18 May 2008) debian
UPSNAME  : natalie
CABLE    : USB Cable
MODEL    : Back-UPS BR  800
UPSMODE  : Stand Alone
STARTTIME: Wed Nov 24 20:30:05 CET 2010
LINEV    : 230.0 Volts
LOADPCT  :  13.0 Percent Load Capacity
BCHARGE  : 100.0 Percent
TIMELEFT :  53.0 Minutes
I made three of then bold, as they will tell you something you need to know. Check that it got the MODEL right. Next, check that STATUS is ONLINE.  Check that LOADPCT is less than 90 (it’s good to have a buffer). Now, on the TIMELEFT it will tell you how long it is able to run on the batteries. If you need now, edit the conf file again and adjust the parameters to fit this, so that you have time to shut down the systems nicely.
Now your UPS setup is working. I know it can be hard, but try pulling the plug for 10 seconds and the connect it again.  You should see a couple of broadcasts on your server. Also, if you view the file /var/log/ you will see all the events that the UPS system logs.
This is a sample of my log (I also tested the shutdown process by making it shut down machines quickly after a power loss.)
Wed Nov 24 20:22:50 CET 2010  Power failure.
Wed Nov 24 20:22:56 CET 2010  Running on UPS batteries.
Wed Nov 24 20:23:57 CET 2010  Reached run time limit on batteries.
Wed Nov 24 20:23:57 CET 2010  Initiating system shutdown!
Wed Nov 24 20:23:57 CET 2010  User logins prohibited
Wed Nov 24 20:24:16 CET 2010  apcupsd exiting, signal 15
Wed Nov 24 20:24:16 CET 2010  apcupsd shutdown succeeded

Make NAS’es shutdown too!

In my case I have 2 NAS’es and I want them to shutdown too. It’s pretty easy to do that (when you figure it out).
This is what I did:
1) ssh-keygen -t rsa
2) mkdir /etc/apcupsd/keys
3) mv ~/.ssh/id_rsa /etc/apcupsd/keys
4) chmod 600 /etc/apcupsd/keys/id_rsa
5) cat ~/.ssh/
Mark and copy the public key.
Log on to your NAS as root/admin account and do “ls -la” – if a .ssh folder is already there, go to it. if not, create it. Check if there is a file called “authorized_keys” – if not, then create it and put the key from your clipholder in it. Now go back to your server and issue this command:
ssh -i /etc/apcupsd/keys/id_rsa -l <username_for_nas> <ip_for_nas> ‘ps’
When you run that, it should show you a process list without any trouble. this process list is from the NAS – this means you can run commands on the NAS via SSH remotely now. In my case the NAS runs busybox, so to shut it down I need to run “/sbin/poweroff” so this will be the full command for me to use:
ssh -i /etc/apcupsd/keys/id_rsa -l admin <ip> ‘/sbin/poweroff’
Test it by running this command and see if your NAS shuts down.
Next thing you need to do is to make apcupsd do this when it shuts down. Do this by editing the file “/etc/apcupsd/apccontrol”
Find the “doshutdown” option and simply add your command BEFORE the ${SHUTDOWN} line. This is mine:
echo “UPS ${2} initiated Shutdown Sequence” | ${WALL}
echo “Will now shutdown NAS systems before killing server” | ${WALL}
/usr/bin/ssh -l admin -i /etc/apcupsd/keys/id_rsa <NAS1_IP> ‘/sbin/poweroff’
/usr/bin/ssh -l admin -i /etc/apcupsd/keys/id_rsa <NAS2_IP> ‘/sbin/poweroff’
${SHUTDOWN} -h now “UPS ${2} initiated shutdown”
And voila! If a power outage occurs your NAS and server will now shut down safely.