Using non-virtualized hardware in a cluster

The drawback to abstracting hardware is that not all hardware can be successfully or practically abstracted to the same degree. For instance, there is currently no practical way to expose a PCI-Express fax card to a Hyper-V guest. As SR-IOV technology advances and becomes more ubiquitous, this may eventually change. For now, the only guaranteed components you have access to are CPU, memory, network, and disk (and video if RemoteFX is configured). That's not quite where the story ends, though.

The most common device type requested for connection is USB, such as for a faxing device or a manufacturer's hardware-enforced license key. Such a device is problematic enough in a single-host environment, but it is compounded in a cluster. By its nature, USB is inherently a single-host architecture. Even if the USB connection were able to be passed through to the guest, the connection would be lost if the guest migrated. So, hardware directly attached to the...