[Nut-upsdev] MGE NMC and NutShutdownModule (and other stuff)

[Arjen de Korte]

Citeren Marco Chiappero <marco op absence.it>:

> Maybe there is something I'm missing, but if that particular machine  
> don't need to go down just do not let it shutdown, it will simply  
> see the low battery flag and notice it.

The problem is, that this flag will never be cleared by an alarm  
message. The NMC does send out alarms that the battery is low, but not  
that the situation has been resolved. In all likelyhood, an NSM client  
will assume the battery isn't low when it starts. But if we continue  
monitoring this NMC, how can we tell without looking at the summary or  
get_object pages? When pressing the test buttons, there will be a  
difference in what the alarm messages tell and what the polled pages  
say. I prefer to let the latter take precedence, since that's also  
more robust when somehow an alarm is missed.

> Maybe, but having a closer look at the network traffic, alarm  
> messages arrive correctly and re-subscription seems to occur randomly.

Could it be that the card is rebooting? If you're running multiple  
clients in parallel, this might trigger an NMC reset. We might need to  
alternate between reading the summary and get_object pages to deal  
with this. Note that if the connection is dropped by the NMC, the  
driver will immediately reconnect. Running the driver in debug mode  
should reveal this.

> There must be something wrong with the socket or the driver.
> BTW, subscription is always succesful.

How do you know the subscription is successful without running the  
driver in debug mode? Currently, the driver won't inform you about that.

>> The driver should periodically receive empty alarm messages from  
>> the NMC. If it doesn't, it assumes the connection is somehow lost  
>> and subscribes again. Do you see the empty alarm messages if you  
>> run the driver with -DD enabled?
> upsdrvctl forks soon after the connection test. How to avoid this?

I already told you how to run netxml-ups in debug mode on Thursday. :-(

Best regards, Arjen
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