[Linux-cluster] fencing loop in a 2-node partitioned cluster

Kein He kein.he at gmail.com
Tue Feb 24 08:05:01 UTC 2009

Hi Rajeev,

there are several ways to stop the fencing loop:

1. import the third node to the cluster, as a result the quorum votes 
will great than half total votes .

2. Using qdisk, you can implement the Tie-Breaker IP: use heuristic 
option to monitor the Gateway. qdisk will also increase the cluster 
votes, makes the total votes an odd number.



Rajeev P wrote:
> Hi,
> I have question regarding a network partition in a 2 node cluster.
> Consider a 2-node cluster (node1 and node2) setup with a cross-cable 
> for heartbeat and setup to use HP iLO as the fencing mechanism. In the 
> event of network partition (and this case assume that the cross cable 
> was pulled out) one of the node's succeed in fencing the other. The 
> question is, when the fenced node on rebooting would it attempt fence 
> the existing node if it can't communicate with it (since the heartbeat 
> network is still down).
> For example consider that in the event of n/w partition, node1 fences 
> node2. Would node2 on rebooting  (can't communicate with node1) would 
> attempt to fence node1 and form a 1-node cluster.
> If yes, can this infinite fencing loop be prevented in 2-node with the 
> use of a qdisk which denies quorum to node rebooting? Appreciate any 
> suggestions to prevent this loop.
> Regards,
> Rajeev
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