Linux/Services/Ups
Shutdown the servers before the Uninterruptible Power Supply is completely drained.
Use case
A Ups is great to avoid hard shutdowns of servers with short power cuts. But what if the power is interrupted for a longer time than the battery can provide the servers? For such cases there is software that shuts down the servers at a certain percentage of battery drainage.
Apcupsd
[[1]] is software specifically for Apc Ups-es. The hardware link between the Ups and a server is (often) a Usb cable. Apc Ups-es come with an odd cable, with on one end a Usb connector and on the other end something that looks like a Utp connector. One server can be connected with the Ups. Other servers must be shutdown from that connected server.
Install
Apcupsd is in the non standard Epel repository.
yum install apcupsd
Connect the usb cable to the Ups and start the service and make it auto start at boot.
Run apcaccess to check if the Ups is found. It will display several parameters of the Ups.
Configure
The configuration files are in the directory/etc/apcupsdThe most interesting variable in apcupsd.conf is
BATTERYLEVEL 50Here it is set to initiate shutdown at 50% battery level.
Basically
Alternatives
Nut is a generic software, suitable for more Ups brands than Apc.