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 Shutdown chapter of this manual.
Master/Slave Networking using NIS and the NET Driver
It is also possible to implement a network of master/slave
apcupsds using the new 3.10.x code and the net driver.
This mode of master/slave networking is considerably different
from the old method described at the beginning of this chapter.
In the old code, there is a lot of configuration on both the
master and slave side, and the master polls or sends info
to the slave. Using the net driver is much simpler.
However, you should carefully check that the slave does
a proper shutdown. In the master/slave code, the master
ensures the best it can that the slave is shutdown or
notified before it shuts down itself. On the other hand,
using the net driver, the master knows nothing about the
slaves that may be listening and thus takes no special
precautions to ensure that the slaves receive the shutdown
signal.
Since the slave reads the master's data
once per second there should be no shutdown problems,
and our experience confirms this.
This point can be answered in your case by carefully
testing the shutdown.
In this master/slave mode, the master is a standard stand alone
configuration except that it must have NETSERVER on
in the configuration file and have an NISPORT nnn defined.
Thus any apcupsd running in this mode then becomes the master.
The slave then uses the net driver to connect to the master's
NIS output. In this mode, the slave decides how often to
poll the master for the NIS information. The
slave copy of apcupsd, have UPSTYPE net, which will invoke
the "network" driver. By setting this machine's DEVICE
to be master-ip:master-NIS-port
it will automatically connect
to the master and use the master's signals to shutdown the computer.
In the example net slave configuration file below, the slave
uses the NIS information provided by the computer tibs
on port 3551.
## apcupsd.conf v1.1 ##
UPSCABLE ether
UPSTYPE net
# Specify the server name:port where NIS is running
DEVICE tibs:3551
LOCKFILE /var/lock
BATTERYLEVEL 5
MINUTES 3
TIMEOUT 0
ANNOY 300
ANNOYDELAY 60
NOLOGON disable
EVENTSFILE /etc/apcupsd/apcupsd.events
UPSCLASS standalone
UPSMODE disable
#
# Use this to control the poll time.
# the default is 60 or 1 minute
#
NETTIME 30