Hi all,

When your cluster nodes got panic while starting cman services that can’t 
called as fence loop that is called as misconfiguration of POST JOIN DELAY 
setting.

By default post_join_delay setting is 3 seconds, while starting cman on a 
cluster node it will try to get the status of other cluster nodes to make sure 
the integrity of the cluster services if other nodes are not responsive till 
post_join_delay timeout, other cluster node fenced by this node to ensure 
integrity (there may be chance that node already formed the cluster and started 
cluster services)

Fence looping is different one, this is happen when there is a failure in heart 
beat switch for long time.

Thanks & Regards

Muthukumar T
Production Engineering - UNIX
9790907286

From: linux-cluster-boun...@redhat.com 
[mailto:linux-cluster-boun...@redhat.com] On Behalf Of Arun G Nair
Sent: Wednesday, June 11, 2014 8:19 PM
To: linux-cluster@redhat.com
Subject: [Linux-cluster] 2-node cluster fence loop

Hello,

   What are the reasons for fence loops when only cman is started ? We have an 
RHEL 6.5 2-node cluster which goes in to a fence loop and every time we start 
cman on both nodes. Either one fences the other. Multicast seems to be working 
properly. My understanding is that without rgmanager running there won't be a 
multicast group subscription ? I don't see the multicast address in 'netstat 
-g' unless rgmanager is running. I've tried to increase the fence 
post_join_delay but one of the nodes still gets fenced.
The cluster works fine if we use unicast UDP.

Thanks,
--
Arun G Nair
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