[Pacemaker] STONITH without mandatory success possible?

[Sven Arnold]

>>
>> echo "0" >  /sys/class/net/virbr0/bridge/multicast_snooping
>
> That results in multicast packets are broadcasted to all bridge ports. I
> prefer to have igmp querier turned on on a central switch.
>
>

I had the impression that the OP used virtual machines on a local 
(virtual and private) network. I had such a setup with my first 
experiments and experienced (timing) issues with corosync messages until 
I turned snooping off.

But you are right, on my production system I have turned on both 
multicast_snooping and multicast_querier.

For reference, there was this bugreport that was helpful for me:
https://bugzilla.redhat.com/show_bug.cgi?id=880035

Regards,

Sven