[Nut-upsuser] Are UPS shutdown commands automatically sent?
roger at rogerprice.org
Sat May 23 10:02:24 UTC 2015
On Fri, 22 May 2015, Rob Groner wrote:
> So I'm pursuing the strategy of issuing the "upsdrvctl shutdown" command
> script when the OS (Porteus, in this case) is shutting down. I so far
> can't get it to do it, but I'm sure I'll overcome it, but I realized
> something else might be a problem.
> Won't that script execute every time Linux is shutting down, including
> rebooting? So, if I choose to reboot my system, I would most likely see
> the UPS shutoff and then turn back on, somewhere in the middle of my
> system booting back up.
Hello Robert, The command /sbin/shutdown -r used to reboot the box is
incompatible with a UPS which receives a delayed shutdown order. If you
have offdelay = 30 in /etc/ups/ups.conf, then 30 seconds after the
upsdrvctl shutdown, when the box has now probably restarted, the UPS will
shutdown with total loss of power to the box. Not good.
> I can think of a couple solutions: 1) Have the script verify that the
> UPS is actually in a OB state before giving the shutdown command. That
> should prevent unintended UPS power cycles when simply rebooting the
> system. 2) Have the UPS itself not respect any "load.off.delay" or
> similar commands when it is online.
This adds complexity, and in a critical system component simplicity is a
virtue. To reboot my box, I turn off the wall power and wait until I hear
the "clunk" as the shutdown relay operates in the UPS. I then turn the
wall power back on.
> Looking over UPS documentation and various helps, it seems most people
> would expect their UPS to turn the load off and then back on, even if it
> has wall power the entire time. That would facilitate testing at a
> minimum. So I'm guessing option #2 isn't a good one.
If you have decided to use a UPS capable of shutting down and restarting
when wall power comes back, then you have to respect the UPS cycle. You
can't pretend it isn't there.
Best regards, Roger
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