[lug] apm/UPS

Anders Knudsen anders at theknudsens.net
Fri Aug 2 12:15:56 MDT 2002

I just got some APC 700's here. They have a serial cable. A linux daemon
came with the UPS. It works well, as I tested it out. It installs a
binary and a startup script (/etc/init.d/upsd). 
It puts entries in /var/log/messages by default. And, when the power
get's too low, it initiates a clean shudown (init 0) automatically.
Rather nice.


On Fri, 2002-08-02 at 11:53, D. Stimits wrote:
> 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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