MANAGER@SKIDMORE.BITNET (Leo Geoffrion) (06/28/88)
We've recently installed an uninterruptible power supply (UPS) in our computer
room. When power fails, the UPS keeps the VAX alive for up to 20 minutes,
allowing a graceful shutdown.
At present, however, we don't have any method for informing the VAX that
a shutdown is needed. Since we do not have 24 hour staffing, an automatic
notification is essential.
The UPS has an RS-232-C port that can inform a computer of what its doing,
but we can't use that because we need to inform several incompatible computers
in addition to the VAX.
Since I have several spare TTxx ports (we've converted users to ethernet
terminal servers), we've envisioned a potential solution as follows:
1. A simple box plugs into 110 Volt (non-UPS) outlet and sends a
constant HI signal to DTR (or DSR) on a TTxx port.
2. If DTR/DSR drops to LO, a process awakes and starts watching
that line.
3. If the line returns to HI, the process informs the console and
goes back to sleep.
4. If the line stays LO for more than a threshold time limit, (e.g.
10 minutes), it launches standard VMS SHUTDOWN.COM for a
graceful shutdown before the UPS batteries die at 20 minutes into
the outage.
In that way, the computer ignores momentary drops in line voltage (we have
many of these), but shutsdown automatically if the line voltage stays low
for more than a few minutes.
Conceptually, the program seems simple enough, and considering the number
of UPS installations nationwide, I'd expect that someone out there has already
done it. Before reinventing wheels, I'd welcome information on what you
are using, as well as copies of any PD solutions that you wish to share.
As usual, if I receive any promising replies, I'll summarize them and post
it.
Thanks, in advance.
===================================================================
Leo D. Geoffrion BITNET: MANAGER@SKIDMORE.BITNET
Associate Director for NYNEX: (518) 584-5000 Ext. 2628
Academic Computing
Skidmore College
Saratoga Springs, NY 12866