Back To My Basics | NPIV


When we discussed about WWN in my Back To My Basics series, we talked about WWNN and WWPN. Normally for a dual port HBA card in a server, there will be two WWPN and one WWNN. This is pretty fine for a normal standalone server. But what if this server is used as a VMware Hypervisor, and one of the VM inside this hypervisor has a requirement to have a direct FC connection to SAN. In the current scenario, it is somewhat possible via RDMs or Raw Device Mapping. For mapping an RDM, a LUN is directly presented to the WWPNs of all ESXi hosts in the cluster and that LUN can be mapped as a RDM disk to the VM. But still the VM is not close enough to the storage and there exists an intermediate, the ESXi, as VM uses the WWPN of the host HBA of ESXi for connectivity. This gap can be bridged using NPIV.

NPIV stands for N_Port ID Virtualization. This is an ANSI T11 standard which enables the mapping of multiple virtual WWNs to a single physical HBA port (WWPN). Now the hypervisor is not limited to the two WWPNs, but has multiple virtual WWNs which can be used based on the requirement from VM. Now the VM has its own WWPN and can directly talk to FC LUN without using the WWPN of ESXi host HBA.

But before using NPIV, you need to confirm that the HBA and FC switch supports NPIV. NPIV will not work if the storage is attached without FC switch. NPIV supports vMotion as the virtual WWN follows the VM during the vMotion activity. But storage vMotion is not supported.


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