The pacemaker_remote service integrates nodes that do not run corosync into the cluster. Pacemaker manages pacemaker_remote resources as it does on any other cluster node.

Among the capabilities that the pacemaker_remote service provides are the following:

• The pacemaker_remote service allows you to scale beyond the Red Hat support limit of 32 nodes.
• The pacemaker_remote service allows you to manage a virtual environment as a cluster resource and also to manage individual services within the virtual environment as cluster resources.

The following terms are used to describe the pacemaker_remote service.

• cluster node - A node running the High Availability services (pacemaker and corosync).
• remote node - A node running pacemaker_remote to remotely integrate into the cluster without requiring corosync cluster membership. A remote node is configured as a cluster resource that uses the ocf:pacemaker:remote resource agent.
• guest node - A virtual guest node running the pacemaker_remote service. The virtual guest resource is managed by the cluster; it is both started by the cluster and integrated into the cluster as a remote node.
• pacemaker_remote - A service daemon capable of performing remote application management within remote nodes and KVM guest nodes in a Pacemaker cluster environment. This service is an enhanced version of Pacemaker’s local executor daemon (pacemaker-execd) that is capable of managing resources remotely on a node not running corosync.

A Pacemaker cluster running the pacemaker_remote service has the following characteristics.

• Remote nodes and guest nodes run the pacemaker_remote service (with very little configuration required on the virtual machine side).
• The cluster stack (pacemaker and corosync), running on the cluster nodes, connects to the pacemaker_remote service on the remote nodes, allowing them to integrate into the cluster.
• The cluster stack (pacemaker and corosync), running on the cluster nodes, launches the guest nodes and immediately connects to the pacemaker_remote service on the guest nodes, allowing them to integrate into the cluster.

The key difference between the cluster nodes and the remote and guest nodes that the cluster nodes manage is that the remote and guest nodes are not running the cluster stack. This means the remote and guest nodes have the following limitations:

• they do not take place in quorum
• they do not run fencing device actions
• they are not eligible to be the cluster’s Designated Controller (DC)
• they do not themselves run the full range of pcs commands

On the other hand, remote nodes and guest nodes are not bound to the scalability limits associated with the cluster stack.

Other than these noted limitations, the remote and guest nodes behave just like cluster nodes in respect to resource management, and the remote and guest nodes can themselves be fenced. The cluster is fully capable of managing and monitoring resources on each remote and guest node: You can build constraints against them, put them in standby, or perform any other action you perform on cluster nodes with the pcs commands. Remote and guest nodes appear in cluster status output just as cluster nodes do.