Primary-backup CRGs and peer CRGs provide resiliency
for resources within a cluster; however, it is important to understand their
differences and uses.
Clusters support two models for defining CRGs in your environment. Roles are defined for both primary-backup and peer models. In primary-backup model, they need to define an order. Nodes that are defined as backup nodes provide access to resources on the primary node in the event of a node failure. With the peer model, each node are equal in the role and can provide access for the resource; however there is no concept of order.
Primary-backup model
With the primary-backup model, users must define the node as either a either primary, backup, or replicate role. These roles are defined and managed within the recovery domain. If a node has been defined as the primary access point for the resource, then other nodes provide backup if the primary node fails.
Peer model
Peer model CRGs eliminate
the need to define an ordered recovery domain. For a peer model, nodes
can be defined as either peer or replicate. If nodes defined as peer, then
all the nodes in the recovery domain are equal and can provide the access
point for the resource.