How to make an external USB drive show up inside a Hyper-V VM

Hyper‑V does not plug a USB port straight into a virtual machine. The host always owns the physical USB controller, and a guest only sees what the host decides to present as storage or redirected devices. That is why a thumb drive may appear as a “redirected” device in an RDP session, but never show up under “Devices and drives” in This PC, or why backup and licensing tools inside the VM fail to detect it.

There are four main ways to bridge that gap, each with different trade‑offs: Enhanced Session Mode redirection, physical disk passthrough, a VHDX file stored on the USB drive, and plain network sharing. There are also edge cases where none of these will help, such as USB dongles that are not storage devices.

Why Hyper‑V VMs do not see USB drives by default

Hyper‑V is built around the idea that virtual machines are portable and independent from specific host hardware. Pinning a VM to a given USB controller would break features like live migration and clustering, so Hyper‑V offers:

• Virtual disks (VHD/VHDX files)
• Passthrough of an entire physical disk as a SCSI device
• Device redirection over a VMConnect / Remote Desktop session

When you plug in a USB drive, Windows on the host claims it, mounts a file system, and exposes it to the user. Hyper‑V does not automatically offer that disk to guests. Until you either redirect it over a virtual session or present it as a disk (physical or virtual), the VM simply has nothing to attach.

Check what kind of USB device you are dealing with

Before trying to “fix” detection inside the VM, confirm whether the USB hardware is a storage device at all. Many licensing dongles and other keys are USB but do not present as disks, so they never appear in tools like Disk Management.

If the device does not appear as a disk, only Enhanced Session Mode / RDP device redirection or specialized USB‑over‑network/DDA setups will help. The VM will never treat it as a local drive.

Option 1: Use Enhanced Session Mode USB redirection

Enhanced Session Mode lets the VM piggy‑back on Remote Desktop’s device redirection, including USB storage. This is usually enough when you simply need to copy files between host and guest and do not care whether the disk is visible as a “native” SCSI drive.

On a client or server that supports it, enable it on the host:

• Open Hyper‑V Manager.
• In the right pane, go to Action > Hyper‑V Settings.
• Under Enhanced Session Mode Policy (for servers) or the equivalent section, enable Use enhanced session mode.

Then connect the VM with VMConnect:

• Double‑click the VM in Hyper‑V Manager to open VMConnect.
• When prompted for connection settings, or from the VMConnect toolbar, open the local resources or USB menu (the USB icon).
• Select the attached USB drive to redirect it to the VM.

Inside the VM, the drive usually appears in File Explorer under a redirected name. Some low‑level software (backup tools, license managers) still may not see it as a “real” disk, because the operating system treats it like a network‑style share backed by RDP, not as hardware on a SCSI controller.

Option 2: Attach the USB drive as a physical disk (passthrough)

Passthrough hands the entire disk to one VM, making it show up as a normal hard drive in Disk Management inside that guest. The host must relinquish control entirely; you cannot use the same USB disk on the host and guest at the same time.

On the host:

• Connect the external USB disk.
• Open Computer Management and go to Disk Management.
• Find the correct disk (for example, “Disk 1”). Right‑click the label area (left side) and choose Offline.

Once the disk is offline on the host, attach it to the VM:

• In Hyper‑V Manager, right‑click the target VM and select Settings.
• Under one of the SCSI Controller entries, select Hard Drive and click Add.
• Choose Physical hard disk, then pick the offline USB disk from the dropdown.
• Apply the changes and start the VM.

Inside the VM, open Disk Management, initialize, and assign a drive letter if needed. The external disk now looks like a normal local drive to the guest, and most disk‑level tools will recognize it.

Important notes:

• While the disk is attached this way, the host cannot use it. It stays offline until you detach it from the VM.
• Checkpoint (snapshot) features on that VM are effectively disabled for that disk, because Hyper‑V cannot snapshot a raw physical device without a VHDX layer.
• If you unplug the USB cable while the VM is running, you risk data loss inside the guest, just as if you pulled a power‑cable on an internal drive.

To safely give the disk back to the host later:

• Shutdown the VM or remove the physical disk from its SCSI controller in the VM’s settings.
• Back on the host’s Disk Management, set the disk back to Online.

Option 3: Put a VHDX file on the USB drive and attach that to the VM

Instead of passing the raw disk through, you can create a virtual disk file (VHDX) on the external drive, then mount that file as a hard disk inside the VM. Hyper‑V handles VHDX natively, which means checkpoints and other management features continue to work, and you can disconnect the external drive more predictably when the VHDX is not in use.

On the host:

• Open Hyper‑V Manager.
• In the Actions pane, select New > Hard Disk.
• Pick the VHDX format and a suitable type (for example, dynamically expanding).
• Choose a size and, when asked where to save the file, point it to the external USB drive.

Attach the VHDX to the VM:

• Open the VM’s settings in Hyper‑V Manager.
• Under a SCSI Controller, add a Hard Drive.
• Select the option to use an existing virtual hard disk and browse to the VHDX file on the USB drive.

Inside the VM, initialize and format the new disk in Disk Management. You can now copy data to it like any other drive. When you are finished and want to unplug the external device:

• Shut down the VM or at least remove the VHDX from the VM’s SCSI controller while it is powered off (safest path).
• Ensure no other VMs have that VHDX attached.
• On the host, eject the USB drive.

This pattern is particularly useful if you need to move the VHDX between multiple hosts or VMs, or you want the protection of checkpoints while still physically storing data on a removable disk.

Option 4: Share the USB drive over the network

Sometimes the simplest method is to treat the host as a file server. You keep full control of the USB disk on the host and just share it over SMB to one or more VMs.

On the Hyper‑V host:

• In File Explorer, right‑click the USB drive and choose Properties.
• Open the Sharing tab and enable Advanced Sharing.
• Give it a share name and configure permissions so that the user account used inside the VM can read or write as needed.

Inside the VM:

• Ensure the VM has network connectivity to the host (default switch or external virtual switch).
• In File Explorer, go to \\<HostComputerName>\<ShareName>.
• Optionally map that path to a drive letter.

This keeps the risk surface small: the USB disk never leaves the host’s control, and you can unplug it after closing open file handles just as you would after copying files from any network share. The trade‑off is that some software inside the VM will still treat it as a network location rather than a local SCSI disk.

When Hyper‑V USB options are not enough

There are cases where none of the above are a good fit:

• Hardware licensing dongles that are not storage devices and must be seen as USB on the bus.
• Specialized USB equipment (lab instruments, card readers) whose drivers expect direct access to a USB controller.

For these, typical workarounds include:

• Using third‑party USB‑over‑Ethernet gateways that present the USB device to the VM over a network protocol.
• Adding a dedicated PCIe USB controller to the host and assigning that entire controller to a VM using Discrete Device Assignment (DDA), where supported.

Both options bypass Hyper‑V’s usual abstractions, so they need careful planning and are usually reserved for highly specific workloads.

Common problems and quick checks

Bridging a USB drive into a Hyper‑V virtual machine is less plug‑and‑play than on desktop‑focused hypervisors, but the available patterns are stable and predictable once you pick the right one. For casual file transfers, Enhanced Session Mode or a network share is usually enough. For tools that demand a local disk, physical passthrough or a VHDX stored on the external drive gives the VM the “real” hard drive it expects, with the caveat that you must treat that disk with the same care as internal storage when it is attached.