Περί UPS

[V13]

On Wednesday 14 November 2007, Christos Ricudis wrote:
> Apaks kai ena mhxanhma apofasisei na kanei shutdown, TO UPS PREPEI
> OPWSDHPOTE NA TOU KOPSEI TO REYMA, estw kai gia ligo.
>
> Opoios mou pei giati to problhma de mporei na ly8ei me eksypnades tou styl
> "mporoume na xrhsimopoihsoume to Wake-on-Lan", kerdizei mpiskoto.

AFAIK einai lymeno. Sto NUT to eksigei kai proteinei kai th lysh:

* Exeis Low battery
* To mixanima ksekinaei shutdown
* San pro-teleytaia entoli, anti gia halt, to mixanima stelnei sima na klisei 
to UPS. Ean exei erthei to reyma, to UPS den klinei.
* Meta apo N deyterolepta to mixanima kanei aytomata reboot. Ean exei prolabei 
na klisei kalos. Ean oxi kanei reboot kai ola kala.

Antigrafo apo to shutdown.txt toy NUT:

-----
Power races
===========

There is a situation where the power may return during the shutdown
process.  This is known as a race.  Here's how we handle it.

"Smart" UPSes typically handle this by using a command that forces the UPS
to power the load off and back on.  This way, you are assured that the
systems will restart even if the power returns at the worst possible
moment.

Contact closure units (ala genericups), on the other hand, have the
potential for a race when feeding multiple systems.  This is due to the
design of most contact closure UPSes.  Typically, the "kill power" line
only functions when running on battery.  As a result, if the line power
returns during the shutdown process, there is no way to power down the
load.

The workaround is to force your systems to reboot after some
interval.  This way, they won't be stuck in the halted state with the UPS
running on line power.
-----

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