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Re: [Linux-cluster] 2-node tie-breaking



Lon H. Hohberger wrote:

[...]

3.  Another simple way to do it is to use a fake "fencing agent" to
introduce a delay:

   <fencedevice agent="/bin/sleep-10" name="sleeper" .../>

(where /bin/sleep-10 is something like:
#!/bin/sh
sleep 10
exit 0
)

Reference that agent as part of -one- node's fencing, and that node will
lose by default.  This way, you don't have to set up qdiskd.  You could
do the same thing by just editing the fencing agent directly on that
node, as well - in which case, you wouldn't have to edit cluster.conf at
all.

Funnily enough, this is exactly what I was just thinking about. Thanks. :-)

Unfortunately, things just got a bit more complicated for me, because it looks like my fencing device won't work. :-( Instead, it may have to end up being something as bodgy as ifdown-ing the cluster interface on the surviving node - in the 2 node scenario, that ought to be as good a using a managed switch based fencing device. The file systems will diverge if both nodes keep running, but neither fork will be corrupted.

Thinking about this a bit more, a tie-breaking IP ping may need to be implemented on the public and private NICs. On the public side, the tie-breaker would need to be the next router along. Are there hooks for implementing such a thing as a simple ping script, or heartbeat or similar that can be used to achieve this?

Thanks.

Gordan


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