9.2.2. Adding a Node to a Cluster
Adding a node to a cluster consists of updating the cluster configuration, propagating the updated configuration to the node to be added, and starting the cluster software on that node. To add a node to a cluster, perform the following steps:
- At any node in the cluster, edit the
/etc/cluster/cluster.confto add aclusternodesection for the node that is to be added. For example, in Example 9.2, “Two-node Cluster Configuration”, if node-03.example.com is supposed to be added, then add aclusternodesection for that node. If adding a node (or nodes) causes the cluster to transition from a two-node cluster to a cluster with three or more nodes, remove the followingcmanattributes from/etc/cluster/cluster.conf:cman two_node="1"expected_votes="1"
Refer to Section 9.2.3, “Examples of Three-Node and Two-Node Configurations” for comparison between a three-node and a two-node configuration. - Update the
config_versionattribute by incrementing its value (for example, changing fromconfig_version="2"toconfig_version="3">). - Save
/etc/cluster/cluster.conf. - (Optional) Validate the updated file against the cluster schema (
cluster.rng) by running theccs_config_validatecommand. For example:[root@example-01 ~]#
ccs_config_validateConfiguration validates - Run the
cman_tool version -rcommand to propagate the configuration to the rest of the cluster nodes. - Verify that the updated configuration file has been propagated.
- Propagate the updated configuration file to
/etc/cluster/in each node to be added to the cluster. For example, use thescpcommand to send the updated configuration file to each node to be added to the cluster. - If the node count of the cluster has transitioned from two nodes to greater than two nodes, you must restart the cluster software in the existing cluster nodes as follows:
- At each node, stop the cluster software according to Section 9.1.2, “Stopping Cluster Software”. For example:
[root@example-01 ~]#
service rgmanager stopStopping Cluster Service Manager: [ OK ] [root@example-01 ~]#service gfs2 stopUnmounting GFS2 filesystem (/mnt/gfsA): [ OK ] Unmounting GFS2 filesystem (/mnt/gfsB): [ OK ] [root@example-01 ~]#service clvmd stopSignaling clvmd to exit [ OK ] clvmd terminated [ OK ] [root@example-01 ~]#service cman stopStopping 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 ~]# - At each node, start the cluster software according to Section 9.1.1, “Starting Cluster Software”. For example:
[root@example-01 ~]#
service cman startStarting 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 startStarting clvmd: [ OK ] Activating VG(s): 2 logical volume(s) in volume group "vg_example" now active [ OK ] [root@example-01 ~]#service gfs2 startMounting GFS2 filesystem (/mnt/gfsA): [ OK ] Mounting GFS2 filesystem (/mnt/gfsB): [ OK ] [root@example-01 ~]#service rgmanager startStarting Cluster Service Manager: [ OK ] [root@example-01 ~]#
- At each node to be added to the cluster, start the cluster software according to Section 9.1.1, “Starting Cluster Software”. For example:
[root@example-01 ~]#
service cman startStarting 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 startStarting clvmd: [ OK ] Activating VG(s): 2 logical volume(s) in volume group "vg_example" now active [ OK ] [root@example-01 ~]#service gfs2 startMounting GFS2 filesystem (/mnt/gfsA): [ OK ] Mounting GFS2 filesystem (/mnt/gfsB): [ OK ] [root@example-01 ~]#service rgmanager startStarting Cluster Service Manager: [ OK ] [root@example-01 ~]# - At any node, using the
clustatutility, verify that each added node is running and part of the cluster. For example:[root@example-01 ~]#
clustatCluster 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) disabledFor information about usingclustat, see Section 9.3, “Managing High-Availability Services”.In addition, you can usecman_tool statusto verify node votes, node count, and quorum count. For example:[root@example-01 ~]#
cman_tool statusVersion: 6.2.0 Config Version: 19 Cluster Name: mycluster Cluster Id: 3794 Cluster Member: Yes Cluster Generation: 548 Membership state: Cluster-Member Nodes: 3 Expected votes: 3 Total votes: 3 Node votes: 1 Quorum: 2 Active subsystems: 9 Flags: Ports Bound: 0 11 177 Node name: node-01.example.com Node ID: 3 Multicast addresses: 239.192.14.224 Node addresses: 10.15.90.58 - At any node, you can use the
clusvcadmutility to migrate or relocate a running service to the newly joined node. Also, you can enable any disabled services. For information about usingclusvcadm, see Section 9.3, “Managing High-Availability Services”
Note
When you add a node to a cluster that uses UDPU transport, you must restart all nodes in the cluster for the change to take effect.
