For any virtualization environment, provisioning storage is one of the biggest ongoing challenges. Also, larger environments that use enterprise fibre channel networks may have additional challenges to provision selective storage to virtual machine infrastructures.

Windows Server 8 and the new Hyper-V role (R3 in this release of Hyper-V) allow an important new feature: guest fibre channel. With guest fibre channel, a specific worldwide port name (WWPN) is assigned to the interfaces inventoried in the virtual machine. This is presented through N_Port ID Virtualization (NPIV) to the Hyper-V host. (If you are not familiar with NPIV, I highly recommend reading Scott Lowe’s blog post explaining the technology. I think it’s hands-down the best resource on the topic.)

The principle of Hyper-V’s guest fibre channel is to maintain the granular zoning of each WWPN for a specific server’s (in this case, a virtual machine) clearly defined storage requirements. This zoning can deliver LUNs to each virtual machine on fibre channel block storage.

Guest fibre channel becomes complicated when multiple hosts are introduced. The guest fibre channel interface has a unique WWPN assigned to that virtual machine. If that virtual machine moves to another host, you need to ensure that connectivity is not interrupted. In traditional fibre channel switching, each physical host has one or more host bus adapters (HBAs). Those HBAs have their own unique WWPN, and may be assigned a zone on the fibre channel switch infrastructure. With a virtual machine having its own WWPN, there would be switch zoning considerations for a migration event. In traditional clusters of virtual machines, each host’s WWPN from the associated HBAs would be grouped together for a zone. In this situation, an additional grouping would be required for the WWPNs of the virtual machines that have guest fibre channel interfaces. The new guest fibre channel interface feature of Windows Server 8 and Hyper-V is shown in Figure A.

Figure A

Windows Server 8 is still only in private developer preview at this point, and this functionality needs thorough consideration as it can increase complexity for storage networks. Does guest fibre channel assignment appeal to you? If so, how would you use it? Share your comments below.