[Nut-upsuser] two MGE Ellipse 1500 ups via usb

[Thomas Gutzler]

Arjen de Korte wrote:
> Citeren Thomas Gutzler <thomas.gutzler at gmail.com>:
> 
>> So when the batteries are critical, the master
>> - sends out FSD to all slaves and touches POWERDOWNFLAG
>> - waits for slaves to disconnect or max HOSTSYNC seconds to pass
>> - waits another FINALDELAY seconds
>> - executes its SHUTDOWNCMD, which
>>   - stops upsd, the drivers and the master upsmon (K50nut)
>>   - stops the nfs server (K80nfs-kernel-server)
>>   - runs upsdrvctl shutdown (S90halt) to shut down the UPSes
>>
>> When a slave detects a FSD, it
>> - processes NOTIFY_SHUTDOWN (send an email in my case)
>> - waits for FINALDELAY seconds
>> - executes its SHUTDOWNCMD instantly, which
>>   - unmounts all nfs drives (S31umountnfs.sh)
>>   - causes upsmon to disconnect and stop (K50nut) and
>>   - shortly after powers off the system (as long as it takes to execute
>> the remaining few shutdown scripts)
>>
>> If that's correct, isn't it better to set FINALDELAY to 0 and increase
>> HOSTSYNC for all slaves rather than increasing FINALDELAY for the
>> master? Shouldn't HOSTSYNC be the time the slowest slave needs to get to
>> the nut shutdown script after receiving a shutdown, which can be delayed
>> by up to POLLFREQALERT seconds?
> 
> The above may work, provided the kill script for NUT isn't run before
> the NFS drives have unmounted. In your setup, this may be true, but this
> may not be so in the general case. Also, the behavior of NUT clients
> when they see the FSD flag is explicitly not defined. They may logout
> from the server immediately and start shutting down only after that. A
> 'FINALDELAY 120' on the NFS system guarantee at *least* 120 seconds for
> the clients to unmount their NFS drives from the moment the FSD flag is
> set. Using 'HOSTSYNC 120' guarantees at *most* 120 seconds (but it could
> be lower as well), so we don't recommend that.

Alright, given the uncertainty, I shall follow your recommendation and
set FINALDELAY to 120 on my master and 5 on the slaves and leave the
HOSTSYNC untouched. Once I've done my first test I will know whether
those numbers are suitable or not.

> You can't use POLLFREQALERT to delay the shutdown.

I didn't mean to. I only mentioned it because it *can* cause another
delay of up to POLLFREQALERT in the shutdown process, which would have
mattered slightly in my above calculation. Although I did set it to 5 so
the delay would have been negligible.

Thanks again for your patience and assistance!

Cheers,
  Tom