On 2008-03-12T16:22:34, "Pinto, Phil (GTI)" <[EMAIL PROTECTED]> wrote:
> >The fact that links get broken completely, but both side can still
> >reach the STONITH device, however is statistically very rare. In
> >fact, connectivity to the STONITH device becomes the "quorum token."
> This may not always true in a virtual environment if two nodes are
> running under a VM and the VM in turn runs a virtual Stonith device.
I didn't say "impossible", I said "statistically very rare". And that it
is - almost always, the broken link means that one side has crashed, or
in the case of a hypervisor, the HVM has broken down.
And, the worst that will happen is that both sides reboot (brief outage)
or shutdown (loss-of-service); while highly undesirable, it is not as
bad as sacrificing correctness.
In any case, almost all the special considerations we discuss here apply
to quorum disks as well - token is token. There is no magic weapon which
never fails - we are always discussing probabilities here, and anyone
who claims 100% certainity is lieing.
(I only do that in executive level presentations at customers, because
they don't like to hear about the theoretical possibilities; but when
we're having an engineering/research level discussion like here, I feel
I must insist on being true about all possible approaches.)
Regards,
Lars
--
Teamlead Kernel, SuSE Labs, Research and Development
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde
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