[Nut-upsuser] Conditionnal shutdown

[Arjen de Korte]

Citeren "Emmanuel Lesouef" <e.lesouef at crbn.fr>:

> Is Upssched the workaround to this ? With a trigger to ONBATT, to wait
> for several minutes (translated to seconds) until shutting down the
> server.

If you want to shutdown your systems before the UPS signals a low  
battery, yes. This may be needed for instance if the remaining runtime  
on battery when the UPS reports 'low battery' is too short for an  
orderly shutdown. Reasons may be a very complex (long) shutdown  
procedure or an exceptionally short runtime remaining (some UPSes will  
shutdown almost immediately after signalling low battery).

But please note however that using 'upssched' to shutdown your systems  
after a fixed time running on battery is not bullet proof (at all). If  
the power returns after a power outage and fails again before the UPS  
battery is fully recharged again, you'd still risk a hard shutdown.  
Likewise, if over time the battery ages (and capacity is reduced) or  
the load increases (more systems connected) it will also fail to  
protect them.

The only real solution to the above problem, is getting yourself a UPS  
that offers both shutdown and restart at certain battery levels and/or  
runtime remaining. Mine will start the shutdown sequence when battery  
charge is down to 50% and it won't restart until the batteries have  
recharged to at least 50%. It will also signal 'low battery' when the  
remaining runtime (with the actual load) is less than two minutes.

Best regards, Arjen
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