A device domain is a subset of nodes in a cluster that share device resources. More specifically, nodes in a device domain can participate in a switching action for some collection of resilient device resources.
Device domains are identified and managed through a set of interfaces that allow you to add a node to a device domain or remove a node from a device domain.
Device domains are used to manage certain global information necessary to switch a resilient device from one node to another. All nodes in the device domain need this information to ensure that no conflicts occur when devices are switched. For example, for a collection of switchable independent disk pools, the independent disk pool identification, disk unit assignments, and virtual address assignments must be unique across the entire device domain.
A cluster node can belong to at most one device domain. Before a node can be added to the recovery domain for a device CRG, the node must be first defined as a member of a device domain. All nodes that will be in the recovery domain for a device CRG must be in the same device domain.
To create and manage device domains, you must have Option 41 (i5/OS™ - HA Switchable Resources) installed and a valid license key on your system.