On Thu, Oct 09, 2008 at 02:56:01PM +0200, Luis Motta Campos wrote:
> Dejan Muhamedagic wrote:
> > Either way would work as you described it. The "custom driver", which
> >  would just be a new stonith plugin doesn't look like very difficult
> >  to implement. We're happy to see contributions :)
> 
> :) I will consider this even if I don't use it myself.
> 
> > Whether that solution would work depends largely on your network 
> > connectivity. How likely it is that neither node can fence the other
> >  side?
> 
> I would say that this is possible, but unlikely. If it happens, I am
> sure we have bigger and nastier problems to solve.
> 
> > Also, if that happens, which would result in both nodes waiting 
> > forever for the fencing operation, does that actually make any 
> > difference to the users?
> 
> If there's no network connectivity, no one is able to reach the database
> in the cluster anyway.
> 
> Your answer made me wonder about what happens when the network comes
> back: will the cluster nodes be able to fence each other at that moment?

Right. Both nodes will wait forever for the stonith action to
succeed.

> What will probably happen to the cluster?

One node would succeed in fencing the other. It's fairly unlikely
that they manage to shoot each other at the same time. In either
case, if the communication is restored, the other node would
reboot (if the stonith-action is set to "reboot") and join the
cluster. You can test that easily by turning off your switch or
similar. At any rate, it's important to test as many different
scenarios as possible.

Thanks,

Dejan

> Thank you very much for the answers.
> Kind regards.
> -- 
> Luis Motta Campos is a software engineer,
> Perl Programmer, foodie and photographer.
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