[Nut-upsuser] 2.2.2-pre2 64 bit rpm tested on openSUSE 10.3

Arjen de Korte nut+users at de-korte.org
Sun Apr 20 19:09:30 UTC 2008

> Hello Arjen, I live in the Alpes Maritimes in the south of France.  This
> is an area with frequent electrical storms, plenty of lightning and it is
> common to have several short power cuts in succession during a storm.  My
> strategy is to tolerate short power cuts, up to 120 seconds, but if the
> power cut lasts longer I tell my users, in french not english, that the
> system is shutting down, and I give them 2 minutes to save their work.
> My time intervals are short because I want to be able to go through the
> shutdown-restart sequence several times without having time to recharge
> the batteries.
> If I lived say in Paris the strategy would be different since there they
> have much less lightning.
> My successive installations of NUT have left me with an accumulation of
> configuration files which have built up over the years.  They could do
> with a thorough cleanup.  I'll have a close look at the upsmon.conf.rpmnew
> which has appeared.

The problem with your configuration is, that it isn't robust (although you
may think it is). When the UPS is reporting a LB condition, your setup
will not allow shortcuts on the delays and you'd still have a two minute
delay in the shutdown command. In all likelyhood, your UPS will not be
able to cope with that when the battery is almost empty. Also, after
sending the 'shutdown -h +2' command, you've effectively lost control over
what happens next.

The better strategy would be to start a upssched timer (I'll call this
'powerout') as soon as the power is lost. If the power returns, cancel the
timer and it is business as usual. When the 'powerout' timer elapses after
two minutes, you start a second timer (I'll call this one 'delayoff')
after sending a message through 'wall' to inform the users that a shutdown
is imminent. Again, if the power returns, you cancel the 'delayoff' timer
(don't forget an informative 'wall' message) and it is business as usual.

When the 'delayoff' timer elapses, you send the master 'upsmon -c fsd'
which will (irreversably) start a shutdown sequence. You also send this
command at any time the UPS reports a low battery condition, whatever the
state of the timers is. This is the part that is missing in your current
configuration. You definitly should *not* add delays when the UPS is
reporting a critical battery, therefor the 2 minute delay in the

Best regards, Arjen
Eindhoven - The Netherlands
Key fingerprint - 66 4E 03 2C 9D B5 CB 9B  7A FE 7E C1 EE 88 BC 57

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