9.4. Updating a Configuration

Updating the cluster configuration consists of editing the cluster configuration file (/etc/cluster/cluster.conf) and propagating it to each node in the cluster. You can update the configuration using either of the following procedures:

9.4.1. Updating a Configuration Using cman_tool version -r

To update the configuration using the cman_tool version -r command, perform the following steps:
  1. At any node in the cluster, edit the /etc/cluster/cluster.conf file.
  2. Update the config_version attribute by incrementing its value (for example, changing from config_version="2" to config_version="3").
  3. Save /etc/cluster/cluster.conf.
  4. Run the cman_tool version -r command to propagate the configuration to the rest of the cluster nodes. It is necessary that ricci be running in each cluster node to be able to propagate updated cluster configuration information.
  5. Verify that the updated cluster.conf configuration file has been propagated. If not, use the scp command to propagate it to /etc/cluster/ in each cluster node.
  6. You may skip this step (restarting cluster software) if you have made only the following configuration changes:
    • Deleting a node from the cluster configuration—except where the node count changes from greater than two nodes to two nodes. For information about deleting a node from a cluster and transitioning from greater than two nodes to two nodes, see Section 9.2, “Deleting or Adding a Node”.
    • Adding a node to the cluster configuration—except where the node count changes from two nodes to greater than two nodes. For information about adding a node to a cluster and transitioning from two nodes to greater than two nodes, see Section 9.2.2, “Adding a Node to a Cluster”.
    • Changes to how daemons log information.
    • HA service/VM maintenance (adding, editing, or deleting).
    • Resource maintenance (adding, editing, or deleting).
    • Failover domain maintenance (adding, editing, or deleting).
    Otherwise, you must restart the cluster software as follows:
    1. At each node, stop the cluster software according to Section 9.1.2, “Stopping Cluster Software”.
    2. At each node, start the cluster software according to Section 9.1.1, “Starting Cluster Software”.
    Stopping and starting the cluster software ensures that any configuration changes that are checked only at startup time are included in the running configuration.
  7. At any cluster node, run cman_tool nodes to verify that the nodes are functioning as members in the cluster (signified as "M" in the status column, "Sts"). For example:
    [root@example-01 ~]# cman_tool nodes
    Node  Sts   Inc   Joined               Name
       1   M    548   2010-09-28 10:52:21  node-01.example.com
       2   M    548   2010-09-28 10:52:21  node-02.example.com
       3   M    544   2010-09-28 10:52:21  node-03.example.com
  8. At any node, using the clustat utility, verify that the HA services are running as expected. In addition, clustat displays status of the cluster nodes. For example:
    [root@example-01 ~]#clustat
    Cluster Status for mycluster @ Wed Nov 17 05:40:00 2010
    Member Status: Quorate
     Member Name                             ID   Status
     ------ ----                             ---- ------
     node-03.example.com                         3 Online, rgmanager
     node-02.example.com                         2 Online, rgmanager
     node-01.example.com                         1 Online, Local, rgmanager
     Service Name                   Owner (Last)                   State         
     ------- ----                   ----- ------                   -----           
     service:example_apache         node-01.example.com            started       
     service:example_apache2        (none)                         disabled
  9. If the cluster is running as expected, you are done updating the configuration.