10.8. Configuring resource groups

One of the most common elements of a cluster is a set of resources that need to be located together, start sequentially, and stop in the reverse order. To simplify this configuration, Pacemaker supports the concept of resource groups.

Creating a resource group

You create a resource group with the following command, specifying the resources to include in the group. If the group does not exist, this command creates the group. If the group exists, this command adds additional resources to the group. The resources will start in the order you specify them with this command, and will stop in the reverse order of their starting order.

# pcs resource group add group_name resource_id [resource_id] ... [resource_id] [--before resource_id | --after resource_id]

You can use the --before and --after options of this command to specify the position of the added resources relative to a resource that already exists in the group.

You can also add a new resource to an existing group when you create the resource, using the following command. The resource you create is added to the group named group_name. If the group group_name does not exist, it will be created.

# pcs resource create resource_id [standard:[provider:]]type [resource_options] [op operation_action operation_options] --group group_name

There is no limit to the number of resources a group can contain. The fundamental properties of a group are as follows.

Additional properties of a group are as follows:

The following example creates a resource group named shortcut that contains the existing resources IPaddr and Email.

# pcs resource group add shortcut IPaddr Email

In this example:

Removing a resource group

You remove a resource from a group with the following command. If there are no remaining resources in the group, this command removes the group itself.

# pcs resource group remove group_name resource_id...

Displaying resource groups

The following command lists all currently configured resource groups.

# pcs resource group list