Author: Kern Sibbald

# Master/Slave Configuration

## General

If you have two or more computers that are powered by the same UPS and they are connected by a network, you can configure apcupsd so that the computer that controls the UPS (connected by the serial port or USB port), which is called the master, can provide information to other machines powered by the UPS, called slaves. When the master detects a power failure, it will notify all the slaves (maximum of twenty). If the master detects that the battery is low, it will also notify the slave so that the slave may perform a shutdown.

In addition, in cases where you wish to keep the master up longer than the slave, you can configure the slave to shutdown in a predetermined time after the UPS goes on batteries.

If a picture is worth a thousand words for you, please see the Three Major Configuration Possibilities for Apcupsd section of the Configuration chapter of this manual.

## Configuration Directives

The minimum set of configuration directive changes needed to create a proper master and slave configuration files is described in the Configuration Examples section of this manual.

The details of these directives is explained in the UPS Sharing section of the Configuration chapter of this document.

In addition, sample master and slave configuration files can be found in the <src>/examples directory (apcupsd.master.conf and apcupsd.slave.conf).

## Master/Slave Problems

If you are having problems getting a master/slave configuration to work, or you are getting error messages, please see the Trouble Shooting Apcupsd Chapter of this manual for more details.

## Master/Slave Shutdown

For additional details of shutting down a master/slave configuration, please see the Master/Slave Shutdown section of the Testing chapter of this manual.