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8.4. 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:

8.4.1. 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 configuration file has been propagated.
  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, refer to Section 8.2, “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, refer to Section 8.2.2, “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 8.1.2, “Stopping Cluster Software”. For example: 
      [root@example-01 ~]# service rgmanager stop
Stopping Cluster Service Manager:                          [  OK  ]
[root@example-01 ~]# service gfs2 stop
Unmounting GFS2 filesystem (/mnt/gfsA):                    [  OK  ]
Unmounting GFS2 filesystem (/mnt/gfsB):                    [  OK  ]
[root@example-01 ~]# service clvmd stop
Signaling clvmd to exit                                    [  OK  ]
clvmd terminated                                           [  OK  ]
[root@example-01 ~]# service cman stop
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  ]
[root@example-01 ~]#
    2. At each node, start the cluster software according to Section 8.1.1, “Starting Cluster Software”. For example: 
      [root@example-01 ~]# service cman start
Starting cluster: 
   Checking Network Manager...                             [  OK  ]
   Global setup...                                         [  OK  ]
   Loading kernel modules...                               [  OK  ]
   Mounting configfs...                                    [  OK  ]
   Starting cman...                                        [  OK  ]
   Waiting for quorum...                                   [  OK  ]
   Starting fenced...                                      [  OK  ]
   Starting dlm_controld...                                [  OK  ]
   Starting gfs_controld...                                [  OK  ]
   Unfencing self...                                       [  OK  ]
   Joining fence domain...                                 [  OK  ]
[root@example-01 ~]# service clvmd start
Starting clvmd:                                            [  OK  ]
Activating VG(s):   2 logical volume(s) in volume group "vg_example" now active
                                                           [  OK  ]
[root@example-01 ~]# service gfs2 start
Mounting GFS2 filesystem (/mnt/gfsA):                      [  OK  ]
Mounting GFS2 filesystem (/mnt/gfsB):                      [  OK  ]
[root@example-01 ~]# service rgmanager start
Starting Cluster Service Manager:                          [  OK  ]
[root@example-01 ~]#
      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.