APC UPS control system - Manual (Page 186)

Configuration section of this manual for more information. See the EEP-
ROM (see Configuring Your EEPROM) of this manual for further details
on how to change these EPROM values.
Shutdown Problems
Obviously if your halt script is not properly modified, apcupsd will not be
able to shut off the power to the UPS, and if the power returns before the
batteries are exhausted your system will not automatically reboot. In any
case, your machine should have been cleanly shut down.
Master/Slave Shutdown
In master/slave configurations, however, the master cannot be 100 percent
sure that the slaves have all shutdown before it performs the power off. As a
consequence, it is possible that the master will shut off the power before the
slave has finished shutdown. If this is the case, the best procedure is to put
an appropriate sleep command in the /etc/apcupsd/apccontrol file on the
master. For example to give the slaves 30 additional seconds to shutdown,
one would add:
sleep 30
just after the line that reads
doshutdown)
in the apccontrol file (approximately line 79 – depending on your system
version).
Also, on a slave machine, you do not want to use the modified halt script
since it will recall apcupsd, which will detect that it is a slave (i.e. no
connection to the UPS) and will complain that it cannot do the killpower.
This situation is not harmful just annoying and possibly confusing.
One possible problem during shutdown can be caused by remnants of
old versions.
Please be sure to delete or rename all prior versions
(/usr/local/sbin/apcupsd or /sbin/powersc).
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