What is Virtual Fibre Channel in the new version of Hyper-V, and what benefits does it bring?
Virtual Fibre Channel (or Guest FC, as some Microsoft documents call it) is a new Hyper-V 3.0 feature that will allow virtual machines to directly connect to Fibre Channel-based storage. This new feature is important for a couple of reasons.
First, Virtual Fibre Channel will make it possible to virtualize servers that require direct Fibre Channel connectivity. Previously, virtualizing such servers was not an option, unless users were willing to give up Fibre Channel connectivity and use SCSI pass-through storage as an alternative.
Another reason why Virtual Fibre Channel is important is it will facilitate clustering of virtual servers over Fibre Channel (which is sometimes referred to as a guest cluster). If such clusters already exist within physical servers, individual cluster nodes can be virtualized one at a time without destroying the cluster in the process and without having to take the clustered resource offline.
Although guest clustering is fully supported, it will be necessary to use affinity and anti-affinity rules to ensure that virtualized cluster nodes never end up residing on a common Hyper-V host server. Such placement would undermine the effectiveness of the cluster because if the host server were to fail, the virtualized cluster nodes that are running on it could also fail (unless the Hyper-V host is also clustered).
The primary requirement that must be met to use Virtual FC is that the underlying SAN must support NPIV (N_Port ID virtualization). Any physical host bus adapters that exist within the host server are shared among the virtual machines (VMs), which means that if you have multiple VMs on a common host that have Virtual Fibre Channel enabled, none of the VMs will receive the full bandwidth that the physical Fibre Channel adapter is capable of providing. It is possible, however, to install multiple host bus adapters into a single Hyper-V host.
This was first published in October 2012