[lug] apm/UPS

D. Stimits stimits at idcomm.com
Fri Aug 2 11:53:07 MDT 2002

I'm looking at an UPS for the Linux bridge and cable modem. Obviously, 
cable modems do not have any "auto power down" feature (nor would the 
modem need it, but not totally depleting a battery's power is good for 
the life of the battery). In the case of the bridge machine, it is 
older, and does not support having the o/s power itself down, it has a 
good old-fashioned switch. However, in the case of the Linux machine, I 
can probably rewrite some of the UPS scripts for apmd, so that it starts 
out by changing the ext3 journal speed from 5 second intervals to 1 
second intervals; and then if time goes far enough, either remount the 
drives read-only, except for /var/, or else run init 0 to halt when 
things get really close.

The above works to protect the Linux machine, but it does not address 
the life of the battery. Can anyone tell me if the UPS itself will shut 
down cleanly at some point, or if it will kill its battery off and not 
stop till the battery is deep discharged?

Also, I am looking at a sale price on a Conext 700 VA UPS, probably it 
is really built by APC or some other company, and just re-labelled for 
Conext. Model number CNB700. Does anyone here have any advice or 
experience with this UPS or this brand of UPS? I'm seeking comments both 
on this brand, and on how an UPS handles itself when the computer itself 
cannot shut itself down...will they kill themselves off? Experiences 
with an UPS fully discharging on a machine without APM support would be 
useful. [perhaps I could init to single user with network, make all 
drives read-only, and issue a command on the serial port to tell the UPS 
to shutdown, if the protocol is known, and it would otherwise kill 
itself off]

D. Stimits, stimits AT idcomm.com

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