Last update 08-Jun-2001
MBSE BBS - Using UPS semaphores.
If you have a UPS and you are able to let your UPS software create semaphores when powerfail conditions
occur then read on. The MBSE BBS taskmanager and a lot of utilities will act on two special semaphores,
they are:
upsalarm, this semafore should be set when there is no mains power, but there is enough
power left to operate your system. All background tasks will be suspended as long as this condition
is true. If the power comes back, the UPS software should remove this semafore.
upsdown, this semafore should be set when the UPS sofware signals your system to go down.
This is a fatal condition and there is no way back. Even if the power comes back your system should
shutdown and the UPS will disconnect the power to your system. After a while it will turn the power on
again and your system boots. MBSE BBS will if this semafore is seen kick users out of the bbs, and the
system shutdown script will try to close MBSE BBS as quick as possible. Normal the close timeout is
one hour to let users normal finnish what they were doing, now it is only 30 seconds and if they were
not logged out, they will be disconnected anyway.
I know not all UPS software can do this but most UPS software is open source so you can change it to create
these semaphores. It is not a problem that UPS semaphores still exist if the systems boots, the MBSE BBS
startup scripts will remove them before the bbs is started.
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