3.2.2. Adding Cluster Nodes


It is highly recommended that you add nodes to existing clusters only during a production maintenance window. This allows you to perform appropriate resource and deployment testing for the new node and its fencing configuration.
Use the following procedure to add a new node to an existing cluster. In this example, the existing cluster nodes are clusternode-01.example.com, clusternode-02.example.com, and clusternode-03.example.com. The new node is newnode.example.com.
On the new node to add to the cluster, perform the following tasks.
  1. Install the cluster packages. If the cluster uses SBD, you must manually install the sbd package on the new node as well.
    [root@newnode ~]# yum install -y pacemaker cman pcs
  2. To prevent corosync from starting without cman, execute the following command:
    [root@newnode ~]# chkconfig corosync off
  3. Set a password for the user ID hacluster. It is recommended that you use the same password for each node in the cluster.
    [root@newnode ~]# passwd hacluster
    Changing password for user hacluster.
    New password:
    Retype new password:
    passwd: all authentication tokens updated successfully.
  4. Start and enable pcsd on the new node:
    [root@newnode ~]# service pcsd start
    [root@newnode ~]# chkconfig pcsd on
On a node in the existing cluster, perform the following tasks.
  1. Authenticate user hacluster on the new cluster node.
    [root@clusternode-01 ~]# pcs cluster auth newnode.example.com
    Username: hacluster
    newnode.example.com: Authorized
  2. Add the new node to the existing cluster. This command also syncs the cluster configuration file cluster.conf to all nodes in the cluster, including the new node you are adding.
    [root@clusternode-01 ~]# pcs cluster node add newnode.example.com
    clusternode-01.example.com: Corosync updated
    clusternode-02.example.com: Corosync updated
    clusternode-03.example.com: Corosync updated
    newnode.example.com: Updated cluster.conf...
    newnode.example.com: Starting Cluster...
On the new node to add to the cluster, perform the following tasks.
  1. Enable cluster services on the new node. In Red Hat Enterprise Linux 6, the new node is started automatically by PCS.
    [root@newnode ~]# pcs cluster enable
  2. Ensure that you configure and test a fencing device for the new cluster node. For information on configuring fencing devices, see Chapter 4, Fencing: Configuring STONITH.