NPIV enables a single FC HBA port to register several unique World Wide Name (WWN) identifiers with the fabric, each of which can be assigned to an individual virtual machine. When using NPIV, a SAN administrator can monitor and route storage access per a virtual machine.

Only virtual machines with RDMs can have WWN assignments, and they use these assignments for all RDM traffic.

When a virtual machine has a WWN assigned to it, the virtual machine’s configuration file (.vmx) is updated to include a WWN pair. The WWN pair consists of a World Wide Port Name (WWPN) and a World Wide Node Name (WWNN). When that virtual machine is powered on, the VMkernel creates a virtual port (VPORT) on the physical HBA which is used to access the LUN. The VPORT is a virtual HBA that appears to the FC fabric as a physical HBA. As its unique identifier, the VPORT uses the WWN pair that was assigned to the virtual machine.

Each VPORT is specific to the virtual machine. The VPORT is destroyed on the host and no longer appears to the FC fabric when the virtual machine is powered off. When a virtual machine is migrated from one host to another, the VPORT closes on the first host and opens on the destination host.

When virtual machines do not have WWN assignments, they access storage LUNs with the WWNs of their host’s physical HBAs.