Fun with APC USV

About two years ago I bought two APC Back-UPS BX. Everything worked fine and they helped to survive one or two power cuts. Occasionally on one of them I got a message about a power outage whereas the other remained silent. Yet everything worked fine and I didn’t pay attention. After a while these messages did not appear again.

Some days ago I wanted to look at the battery state and was quite surprised to only get an error message about a lost connection to the USV. The USV was not available on the USB bus and disconnecting/connecting the USV or rebooting the attached computer did not help. I had to switch off the USV, really pull the plug and wait sometime. Afterwards everything worked fine again. Of course the other one had the same problem :-(.

And the moral of this story: Missing messages might have a reason and if something can fail, write a test and let nagios (or icinga or check_mk or whatever) tell you that there is something wrong.