10.2. Cluster Does Not Form

If you find you are having trouble getting a new cluster to form, check for the following things:

Make sure you have name resolution set up correctly. The cluster node name in the cluster.conf file should correspond to the name used to resolve that cluster's address over the network that cluster will be using to communicate. For example, if your cluster's node names are nodea and nodeb make sure both nodes have entries in the /etc/cluster/cluster.conf file and /etc/hosts file that match those names.
If the cluster uses multicast for communication between nodes, make sure that multicast traffic is not being blocked, delayed, or otherwise interfered with on the network that the cluster is using to communicate. Note that some Cisco switches have features that may cause delays in multicast traffic.
Use telnet or SSH to verify whether you can reach remote nodes.
Execute the ethtool eth1 | grep link command to check whether the ethernet link is up.
Use the tcpdump command at each node to check the network traffic.
Ensure that you do not have firewall rules blocking communication between your nodes.
Ensure that the interfaces the cluster uses for inter-node communication are not using any bonding mode other than 0, 1, or 2. (Bonding modes 0 and 2 are supported as of Red Hat Enterprise Linux 6.4.)