[Nut-upsuser] sequence of events / timing upssched/master/slave etc

Charles Lepple clepple at gmail.com
Sat Jan 26 18:02:17 UTC 2008

On Jan 25, 2008, at 10:39 AM, Olaf Zevenboom wrote:

> Dear List,
> I am a bit uncertain about some aspects of NUT and have not been  
> able to
> find the desired info in the documentation.
> We have a server monitoring the network and it is also running the
> ups/nut-daemon. Together with some other important servers (all Linux)
> it is logical to make these monitor the UPS as 'master'. While other
> servers (mostly windows running winnut, some linux) can be  
> configured to
> monitor the ups daemon as slaves.
> The server running the daemon is configured to use upssched.
> The questions are:
> - flags/events : are these broadcasted to other servers so upssched is
> only useful to control the server running the daemon itself? Or are  
> the
> events only passed on after the timer of upssched is completed?

If I understand the way you're thinking about the events, we have a  
slightly different way of broadcasting from the way you describe it.

Modulo the access rules, any machine can use upsmon to connect to the  
master. So in that sense, the events that trigger upsmon actions are  
"broadcast" (not in the networking sense) to any connected machine.

> - can events/flags be manipulated? (from within the upssched script on
> the server running the deamon)

You can cancel running timers and force a shutdown, but that's all I  
know how to do. (Someone else more familiar with upssched might have  
some other insights.)

> - can upssched also be implemented on windows machines?

It's possible, but I don't know how well the code will compile on  
Windows. Have you checked to see if WinNut has the capabilities you  

> - how do servers configured as NUT master handle stale servers
> configured as slaves? Do they keep waiting?

Do you mean "stale" as defined in the "Dead UPSes" section of the  
upsmon(8) man page? Also check out "HOSTSYNC" in upsmon.conf(5).

> - one of the servers is a Virtual Machine server running various VMs.
> These VMs aswel as the server itself all run NUT but an extra  
> dependency
> is introduced here. The main server must de downed last. Any  
> insights on
> this?

This probably depends on your VM, but in VMWare, you can configure  
the host system to gracefully shut down the guest OSes as part of the  
host shutdown process. You will most likely need to extend some of  
the timeouts to account for this extra shutdown time.

I think you can also set a longer delay in your SHUTDOWNCMD  
commandline on the host upsmon.conf than what you use in the slaves,  
but that will not account for variations in the amount of time it  
takes to shut down the guests.

Charles Lepple
clepple at gmail

More information about the Nut-upsuser mailing list