At 11:01 PM 3/8/2012, Charles Lepple wrote:
[Snip]
> EPO on the other hand is a key requirement of my next feature: The
> ability of a UPS driver to declare that the UPS is dying of some
> critical condition and that it must be shut down in such a way that
> manual human intervention is required to restart it. EPO is also
> intended to be triggered automatically, whereas FSD (I think) is always
> intended to be manually introduced by a human systems manager.
>
> I.e. in an ideal configuration everything should restart and reboot and
> return to operational status after "upsmon -c fsd" once mains power
> returns or if power was never actually off; whereas with "upsmon -c epo"
> then everything should power down and stay off even if mains power
> remains on and steady.
This is an interesting distinction (one that a few drivers make in
their different shutdown commands, but that is not currently tied to FSD).
The reason why I advocated usurping the "FSD" status was because it
is the only other status besides "OB LB" that is currently
guaranteed to trigger a shutdown. I wonder if we could just use FSD
with some other status option to indicate whether the driver should
request a restart when the power returns.
I've CC'd Bill Elliot to get his thoughts on the use cases that led
to suggesting the external shutdown trigger - it might dovetail with this.
> For example I would have used "FSD" to shut down in power blackouts
> where I knew the power could not return before the batteries ran low,
> and thus I would have conserved battery charge for the inevitable short
> hiccups that occur after a long blackout, but still been able to enjoy
> automatic restart after the blackout in case power returns while I'm
> sleeping, etc.
>
Just my .02. The action the UPS takes when power is restored is
(should be?) independent of the use of "FSD". The driver can
configure the UPS to do what is required for the given environmental
information before issuing "FSD". This would be similar to the
difference between the "shutdown.return" and "shutdown.stayoff"
commands...but driven by driver logic.
The reason that I brought the use of "FSD" up initially was that the
UPS I was working with had multiple communication channels to it and
the channel that NUT was not using could initiate a UPS shutdown. In
that case the driver could see that a shutdown timer was active and
issue the "FSD" so the computers being powered by the UPS could do a
graceful shutdown.
Bill
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