[Nut-upsuser] Are UPS shutdown commands automatically sent?

Roger Price 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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