9.2. Deleting or Adding a Node
This section describes how to delete a node from a cluster and add a node to a cluster. You can delete a node from a cluster according to Section 9.2.1, “Deleting a Node from a Cluster”; you can add a node to a cluster according to Section 9.2.2, “Adding a Node to a Cluster”.
9.2.1. Deleting a Node from a Cluster
Deleting a node from a cluster consists of shutting down the cluster software on the node to be deleted and updating the cluster configuration to reflect the change.
Important
If deleting a node from the cluster causes a transition from greater than two nodes to two nodes, you must restart the cluster software at each node after updating the cluster configuration file.
To delete a node from a cluster, perform the following steps:
- At any node, use the
clusvcadmutility to relocate, migrate, or stop each HA service running on the node that is being deleted from the cluster. For information about usingclusvcadm, see Section 9.3, “Managing High-Availability Services”. - At the node to be deleted from the cluster, 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 any node in the cluster, edit the
/etc/cluster/cluster.confto remove theclusternodesection of the node that is to be deleted. For example, in Example 9.1, “Three-node Cluster Configuration”, if node-03.example.com is supposed to be removed, then delete theclusternodesection for that node. If removing a node (or nodes) causes the cluster to be a two-node cluster, you can add the following line to the configuration file to allow a single node to maintain quorum (for example, if one node fails):<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.
- If the node count of the cluster has transitioned from greater than two nodes to two nodes, you must restart the cluster software 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 any cluster node, run
cman_tool nodesto 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 nodesNode 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 - At any node, using the
clustatutility, verify that the HA services are running as expected. In addition,clustatdisplays status of the cluster nodes. For example:[root@example-01 ~]#
clustatCluster Status for mycluster @ Wed Nov 17 05:40:00 2010 Member Status: Quorate Member Name ID Status ------ ---- ---- ------ 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
