vSphere Storage - ESXi 5.0 - Documentation - VMware

vSphere Storage
If NPIV is enabled, WWN pairs (WWPN & WWNN) are specified for each virtual machine at creation time.
When a virtual machine using NPIV is powered on, it uses each of these WWN pairs in sequence to try to
discover an access path to the storage. The number of VPORTs that are instantiated equals the number of
physical HBAs present on the host. A VPORT is created on each physical HBA that a physical path is found
on. Each physical path is used to determine the virtual path that will be used to access the LUN. Note that
HBAs that are not NPIV-aware are skipped in this discovery process because VPORTs cannot be instantiated
on them.
Requirements for Using NPIV
If you plan to enable NPIV on your virtual machines, you should be aware of certain requirements.
The following requirements exist:
n NPIV can be used only for virtual machines with RDM disks. Virtual machines with regular virtual disks
use the WWNs of the host’s physical HBAs.
n HBAs on your host must support NPIV.
For information, see the vSphere Compatibility Guide and refer to you vendor documentation.
n Use HBAs of the same type, either all QLogic or all Emulex. VMware does not support heterogeneous
HBAs on the same host accessing the same LUNs.
n If a host uses multiple physical HBAs as paths to the storage, zone all physical paths to the virtual
machine. This is required to support multipathing even though only one path at a time will be active.
n Make sure that physical HBAs on the host have access to all LUNs that are to be accessed by NPIVenabled
virtual machines running on that host.
n The switches in the fabric must be NPIV-aware.
n When configuring a LUN for NPIV access at the storage level, make sure that the NPIV LUN number and
NPIV target ID match the physical LUN and Target ID.
n Use the vSphere Client to manipulate virtual machines with WWNs.
NPIV Capabilities and Limitations
Learn about specific capabilities and limitations of the use of NPIV with ESXi.
ESXi with NPIV supports the following items:
n NPIV supports vMotion. When you use vMotion to migrate a virtual machine it retains the assigned
WWN.
If you migrate an NPIV-enabled virtual machine to a host that does not support NPIV, VMkernel reverts
to using a physical HBA to route the I/O.
n If your FC SAN environment supports concurrent I/O on the disks from an active-active array, the
concurrent I/O to two different NPIV ports is also supported.
When you use ESXi with NPIV, the following limitations apply:
n Because the NPIV technology is an extension to the FC protocol, it requires an FC switch and does not
work on the direct attached FC disks.
n When you clone a virtual machine or template with a WWN assigned to it, the clones do not retain the
WWN.
n NPIV does not support Storage vMotion.
n Disabling and then re-enabling the NPIV capability on an FC switch while virtual machines are running
can cause an FC link to fail and I/O to stop.
40 VMware, Inc.