Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux

B.3.4. Creating the Resources and Resource Groups with the pcs Command

This use case requires that you create four cluster resources. To ensure these resources all run on the same node, they are configured as part of the resource group apachegroup. The resources to create are as follows, listed in the order in which they will start.
  1. An LVM resource named my_lvm that uses the LVM volume group you created in Section B.3.1, “Configuring an LVM Volume with an ext4 File System”.
  2. A Filesystem resource named my_fs, that uses the filesystem device /dev/my_vg/my_lv you created in Section B.3.1, “Configuring an LVM Volume with an ext4 File System”.
  3. An IPaddr2 resource, which is a floating IP address for the apachegroup resource group. The IP address must not be one already associated with a physical node. If the IPaddr2 resource's NIC device is not specified, the floating IP must reside on the same network as the statically assigned IP addresses used by the cluster nodes, otherwise the NIC device to assign the floating IP address cannot be properly detected.
  4. An apache resource named Website that uses the index.html file and the Apache configuration you defined in Section B.3.2, “Web Server Configuration”.
The following procedure creates the resource group apachegroup and the resources that the group contains. The resources will start in the order in which you add them to the group, and they will stop in the reverse order in which they are added to the group. Run this procedure from one node of the cluster only.
  1. The following command creates the LVM resource my_lvm. This command specifies the exclusive=true parameter to ensure that only the cluster is capable of activating the LVM logical volume. Because the resource group apachegroup does not yet exist, this command creates the resource group.
    [root@z1 ~]# pcs resource create my_lvm LVM volgrpname=my_vg \
    exclusive=true --group apachegroup
    When you create a resource, the resource is started automatically. You can use the following command to confirm that the resource was created and has started.
    # pcs resource show
     Resource Group: apachegroup
         my_lvm	(ocf::heartbeat:LVM):	Started
    You can manually stop and start an individual resource with the pcs resource disable and pcs resource enable commands.
  2. The following commands create the remaining resources for the configuration, adding them to the existing resource group apachegroup.
    [root@z1 ~]# pcs resource create my_fs Filesystem \
    device="/dev/my_vg/my_lv" directory="/var/www" fstype="ext4" --group \
    [root@z1 ~]# pcs resource create VirtualIP IPaddr2 ip= \
    cidr_netmask=24 --group apachegroup
    [root@z1 ~]# pcs resource create Website apache \
    configfile="/etc/httpd/conf/httpd.conf" \
    statusurl="" --group apachegroup
  3. After creating the resources and the resource group that contains them, you can check the status of the cluster. Note that all four resources are running on the same node.
    [root@z1 ~]# pcs status
    Cluster name: my_cluster
    Last updated: Wed Jul 31 16:38:51 2013
    Last change: Wed Jul 31 16:42:14 2013 via crm_attribute on
    Stack: corosync
    Current DC: (2) - partition with quorum
    Version: 1.1.10-5.el7-9abe687
    2 Nodes configured
    6 Resources configured
    Online: [ ]
    Full list of resources:
     myapc	(stonith:fence_apc_snmp):	Started 
     Resource Group: apachegroup
         my_lvm	(ocf::heartbeat:LVM):	Started 
         my_fs	(ocf::heartbeat:Filesystem):	Started 
         VirtualIP	(ocf::heartbeat:IPaddr2):	Started 
         Website	(ocf::heartbeat:apache):	Started
    Note that if you have not configured a fencing device for your cluster, as described in Section B.2, “Fencing Configuration”, by default the resources do not start.
  4. Once the cluster is up and running, you can point a browser to the IP address you defined as the IPaddr2 resource to view the sample display, consisting of the simple word "Hello".
    If you find that the resources you configured are not running, you can run the pcs resource debug-start resource command to test the resource configuration. For information on the pcs resource debug-start command, see the High Availability Add-On Reference manual.