You can modify WWN assignments for a virtual machine with an RDM.

Typically, you do not need to change existing WWN assignments on your virtual machine. In certain circumstances, for example, when manually assigned WWNs are causing conflicts on the SAN, you might need to change or remove WWNs.


Launch the vSphere Client and log in to a vCenter Server system or an ESXi host.

Make sure to power off the virtual machine if you want to edit the existing WWNs.

Before you begin, ensure that your SAN administrator has provisioned the storage LUN ACL to allow the virtual machine’s ESXi host to access it.


  1. Open the Virtual Machine Properties dialog box by clicking the Edit Settings link for the selected virtual machine.
  2. Click the Options tab and select Fibre Channel NPIV.
    The Virtual Machine Properties dialog box opens.
  3. Edit the WWN assignments by selecting one of the following options:
    Option Description
    Temporarily disable NPIV for this virtual machine Disable the WWN assignments for the virtual machine.
    Leave unchanged The existing WWN assignments are retained. The read-only WWN Assignments section of this dialog box displays the node and port values of any existing WWN assignments.
    Generate new WWNs New WWNs are generated and assigned to the virtual machine, overwriting any existing WWNs (those of the HBA itself are unaffected).
    Remove WWN assignment The WWNs assigned to the virtual machine are removed and it uses the HBA WWNs to access the storage LUN. This option is not available if you are creating a new virtual machine.
  4. Click OK to save your changes.