[Pacemaker] Mail notification for fencing action

[mark - pacemaker list]

On Wed, Jun 15, 2011 at 12:24 PM, imnotpc <imnotpc at rock3d.net> wrote:

>
> What I was thinking is that the DC is never fenced


Is this actually the case?  It would sure explain the one "gotcha" I've
never been able to work around in a three node cluster with stonith/SBD.  If
you unplug the network cable from the DC (but it and the other nodes all
still see the SBD disk via their other NIC(s)), the DC of course becomes
completely isolated.  It will fence one of the still good nodes right away,
and the surviving node that still has network connectivity will become DC.
 So, you have two DCs, the original one which is disconnected from the
network and your newly elected one (not really elected, just took over
because it's the last host left that has network).  When the just-fenced
node comes back up, you get quorum with the new DC and your disconnected DC
finally gets shot.

For any non-DC node, you get exactly the behavior you'd expect, where
unplugging its network cable gets it fenced and everyone else stays happy.
 I'd hoped for a situation where unplugging the DC would have the other two
say, "well, our DC is gone, but we can see each other so he need to be
fenced".  Maybe I've just missed a necessary timeout setting somewhere to
delay the isolated DC from fencing a good node so quickly?

Sorry, I guess that's a thread hijack, but I've looked and googled and never
anywhere been able to find something that says DCs don't get fenced, so this
has confused me for a bit.

Regards,
Mark
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