Creating a resource group

You can 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_nameresource_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_actionoperation_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.

• Resources are colocated within a group.
• Resources are started in the order in which you specify them. If a resource in the group cannot run anywhere, then no resource specified after that resource is allowed to run.
• Resources are stopped in the reverse order in which you specify them.

Additional properties of a group are as follows:

• You can set the following options for a resource group, and they maintain the same meaning as when they are set for a single resource: priority, target-role, is-managed. For information about resource meta options, see Configuring resource meta options.
• Stickiness, the measure of how much a resource wants to stay where it is, is additive in groups. Every active resource of the group will contribute its stickiness value to the group’s total. So if the default resource-stickiness is 100, and a group has seven members, five of which are active, then the group as a whole will prefer its current location with a score of 500.

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:

• The IPaddr is started first, then Email.
• The Email resource is stopped first, then IPAddr.
• If IPaddr cannot run anywhere, neither can Email.
• If Email cannot run anywhere, however, this does not affect IPaddr.

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_nameresource_id...

Displaying resource groups

The following command lists all currently configured resource groups.

# pcs resource group list