Q. Can I use SMB Direct within a Hyper-V VM?
A. SMB Direct enables SMB to utilize RDMA capabilities of network adapters which enables very fast data transfers with very little host resource utilization as all the data transfer is offloaded to the network adapters. For SMB Direct to function the SMB stack needs to have direct access to the RDMA hardware with nothing in-between. This means if an RDMA capable NIC is connected to a virtual switch the RDMA capabilities are lost which means SMB Direct will not function from within a Hyper-V VM. Note RDMA capabilities are also lost if you team RDMA network adapters or use SR-IOV.