shutdown by regular user

[Karl Auer]

On Fri, 2015-03-27 at 06:44 +0100, Nils Kassube wrote:
> Not necessarily: /tmp is usually cleared at bootup. :)

True - but the kill-me file might not be in /ŧmp, a failure during
bootup might leave the file there accidentally, and it's good
housekeeping, anyway.

> Why use the power swtich of the UPS, if the power switch of the computer 
> does the job. Granted, you can't use this method as an excuse to spend 
> the money for the UPS. :)

If the power switch on the computer causes an orderly shutdown with no
further user input, then yes, the power switch on the computer is the
way to go. However, this is often not the case - either the system wants
more input, OR hitting the switch causes an immediate power-down, not an
orderly shutdown. Many systems will ask for confirmation if the button
is pressed - but will power down hard if the button is held down for a
few seconds.

When you pull the power on a UPS, it generally signals at least one
device (typically an attached server) so that the device can shut itself
down in an orderly fashion before the standby power runs out. Typically
either the UPS can signal other devices or the first device signalled
can pass it on, so that other supported devices can shut themselves down
too.

If you run your UPS any other way, the what you really have is no more
than a glitch-bridger. It will iron out over- and under-voltages, and it
will bridge short outages, but if the power goes out for any real length
of time the batteries will die and the attached systems will go down
just the same way they would have without the UPS - namely hard.

Regards, K.

-- 
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Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer
http://twitter.com/kauer389

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