On Wed, Oct 19, 2011 at 12:12:02PM +0200, Maurice Janssen wrote: > Op Wo, 19 oktober, 2011 11:41, schreef Paul de Weerd: > > So .. what is the fundamental difference from a 'real' UPS that can > > signal the machine itself that power is going down ? You get to do > > the same steps "in case power is restored while we're going down". > > > > The difference is that a smart UPS can be told to kill the power in the > rc.shutdown script. > If the UPS does what it is supposed to do, it will kill the power to the > computer and wait until the power is restored or it will cycle the power > to the computer if the power comes back after the 'kill power command' is > received but before the power is killed. > > Maurice
Also, a smart UPS can be told not to apply power to the machine until it has reached a sufficient (settable) charge level after the power comes back. If the power comes back and disappears again, which is not too uncommon when all starting devices on the power network causes overload; without sufficient charge level the machine may not have time to even start properly before the battery is completely drained, and thus fails to detect UPS on battery and do a shutdown. -- / Raimo Niskanen, Erlang/OTP, Ericsson AB
