[plug] UPS's

[Brad Campbell]

Colin Muller wrote:
> 
> I'd really appreciate it if someone could tell me (or a pointer to one)
> what happens at point 5 below in a well-designed setup (and how it
> happens):
> 
> 1. Power fails, UPS continues providing power
> 2. Power not being restored, UPS lets computer know via serial line and
> PM software that power is getting low.
> 3. Computer shuts down (or as Matt suggested, goes into single-user
> mode)
> 4. Power is restored.
> 5. ???
> 
> Obviously, the ideal would be that in 5, the computer powers up again
> (or returns to networked multi-user mode). How is this achieved?

Simple with my UPS.. the UPS still shuts down, then powers up again about 30 seconds later
ensuring the computer re-boots..
With mine, the sequence is as follows..

- Mains Fails, UPS tells computer mains has failed and gives it a battery status
- PC polls for battery status every couple of seconds, and from this determines an estimated
runtime.
- UPS daemon decides batteries are getting low after x minutes and tells the ups to shutdown
in x seconds, it then tells the computer to do a poweroff.
- the computer shuts down cleanly, and sits there until the ups powers off. The ups WILL power
off, after the X seconds, regardless of the mains status, it then waits (I think) about 30
seconds, and powers back up again, if mains is present.
Simple, and works every time.
Cheap too, I think the ups was only a couple of hundred $

-- 
Brad....
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