Starting a recently added cluster node fails with "Waiting for quorum... Timed-out waiting for cluster" in a RHEL 6 High Availability cluster using the UDPU transport

Issue

• I'm trying to increase a 3 node-cluster to 4 nodes, but I’m not able to get a quorum when I try to start cman on the new node.

# ccs -h node4.example.com --startall
[...]
Unable to start node4.example.com, possibly due to lack of quorum, try --startall
Error: service cman start failed:

• We added a new node to the cluster, but starting cman fails with "Timed-out waiting for cluster"

[root@rhel6-node4 ~]# service cman start
Starting cluster: 
   Checking if cluster has been disabled at boot...        [  OK  ]
   Checking Network Manager...                             [  OK  ]
   Global setup...                                         [  OK  ]
   Loading kernel modules...                               [  OK  ]
   Mounting configfs...                                    [  OK  ]
   Starting cman...                                        [  OK  ]
   Waiting for quorum... Timed-out waiting for cluster
                                                           [FAILED]
Stopping cluster: 
   Leaving fence domain...                                 [  OK  ]
   Stopping gfs_controld...                                [  OK  ]
   Stopping dlm_controld...                                [  OK  ]
   Stopping fenced...                                      [  OK  ]
   Stopping cman...                                        [  OK  ]
   Waiting for corosync to shutdown:                       [  OK  ]
   Unloading kernel modules...                             [  OK  ]
   Unmounting configfs...                                  [  OK  ]

• I can't add a node to a UDPU cluster