8.5.2. Adding a Cluster Service to the Cluster

To add a cluster service to the cluster, follow the steps in this section.

Note

The examples provided in this section show a cluster service in which all of the resources are at the same level. For information on defining a service in which there is a dependency chain in a resource hierarchy, as well as the rules that govern the behavior of parent and child resources, see Appendix C, HA Resource Behavior.
  1. Open /etc/cluster/cluster.conf at any node in the cluster.
  2. Add a service section within the rm element for each service. For example: 
    
    <rm>
        <service autostart="1" domain="" exclusive="0" name="" recovery="restart">

        </service>
    </rm>
  3. Configure the following parameters (attributes) in the service element:
    • autostart — Specifies whether to autostart the service when the cluster starts. Use '1' to enable and '0' to disable; the default is enabled.
    • domain — Specifies a failover domain (if required).
    • exclusive — Specifies a policy wherein the service only runs on nodes that have no other services running on them.
    • recovery — Specifies a recovery policy for the service. The options are to relocate, restart, disable, or restart-disable the service.
  4. Depending on the type of resources you want to use, populate the service with global or service-specific resources
    For example, here is an Apache service that uses global resources: 
    
    <rm>
        <resources>
                <fs name="web_fs" device="/dev/sdd2" mountpoint="/var/www" fstype="ext3"/>
                <ip address="127.143.131.100" monitor_link="yes" sleeptime="10"/>
                <apache config_file="conf/httpd.conf" name="example_server" server_root="/etc/httpd" shutdown_wait="0"/>
        </resources>
        <service autostart="1" domain="example_pri" exclusive="0" name="example_apache" recovery="relocate">
                <fs ref="web_fs"/>
                <ip ref="127.143.131.100"/>
                <apache ref="example_server"/>
        </service>
    </rm>
    For example, here is an Apache service that uses service-specific resources: 
    
    <rm>
        <service autostart="0" domain="example_pri" exclusive="0" name="example_apache2" recovery="relocate">
                <fs name="web_fs2" device="/dev/sdd3" mountpoint="/var/www2" fstype="ext3"/>
                <ip address="127.143.131.101" monitor_link="yes" sleeptime="10"/>
                <apache config_file="conf/httpd.conf" name="example_server2" server_root="/etc/httpd" shutdown_wait="0"/>
        </service>
    </rm>
    Example 8.10, “cluster.conf with Services Added: One Using Global Resources and One Using Service-Specific Resources ” shows an example of a cluster.conf file with two services:
    • example_apache — This service uses global resources web_fs, 127.143.131.100, and example_server.
    • example_apache2 — This service uses service-specific resources web_fs2, 127.143.131.101, and example_server2.
  5. Update the config_version attribute by incrementing its value (for example, changing from config_version="2" to config_version="3">).
  6. Save /etc/cluster/cluster.conf.
  7. (Optional) Validate the updated file against the cluster schema (cluster.rng) by running the ccs_config_validate command. For example: 
    [root@example-01 ~]# ccs_config_validate 
Configuration validates
  8. Run the cman_tool version -r command to propagate the configuration to the rest of the cluster nodes.
  9. Verify that the updated configuration file has been propagated.
  10. Proceed to Section 8.9, “Verifying a Configuration”.

Example 8.10. cluster.conf with Services Added: One Using Global Resources and One Using Service-Specific Resources 


<cluster name="mycluster" config_version="3">
   <clusternodes>
     <clusternode name="node-01.example.com" nodeid="1">
         <fence>
            <method name="APC">
              <device name="apc" port="1"/>
             </method>
         </fence>
     </clusternode>
     <clusternode name="node-02.example.com" nodeid="2">
         <fence>
            <method name="APC">
              <device name="apc" port="2"/>
            </method>
         </fence>
     </clusternode>
     <clusternode name="node-03.example.com" nodeid="3">
         <fence>
            <method name="APC">
              <device name="apc" port="3"/>
            </method>
         </fence>
     </clusternode>
   </clusternodes>
   <fencedevices>
         <fencedevice agent="fence_apc" ipaddr="apc_ip_example" login="login_example" name="apc" passwd="password_example"/>
   </fencedevices>
   <rm>
       <failoverdomains>
           <failoverdomain name="example_pri" nofailback="0" ordered="1" restricted="0">
               <failoverdomainnode name="node-01.example.com" priority="1"/>
               <failoverdomainnode name="node-02.example.com" priority="2"/>
               <failoverdomainnode name="node-03.example.com" priority="3"/>
           </failoverdomain>
       </failoverdomains>
       <resources>
           <fs name="web_fs" device="/dev/sdd2" mountpoint="/var/www" fstype="ext3"/>
           <ip address="127.143.131.100" monitor_link="yes" sleeptime="10"/>
           <apache config_file="conf/httpd.conf" name="example_server" server_root="/etc/httpd" shutdown_wait="0"/>
       </resources>
       <service autostart="1" domain="example_pri" exclusive="0" name="example_apache" recovery="relocate">
           <fs ref="web_fs"/>
           <ip ref="127.143.131.100"/>
           <apache ref="example_server"/>
       </service>
       <service autostart="0" domain="example_pri" exclusive="0" name="example_apache2" recovery="relocate">
           <fs name="web_fs2" device="/dev/sdd3" mountpoint="/var/www2" fstype="ext3"/>
           <ip address="127.143.131.101" monitor_link="yes" sleeptime="10"/>
           <apache config_file="conf/httpd.conf" name="example_server2" server_root="/etc/httpd" shutdown_wait="0"/>
       </service>
   </rm>
</cluster>