If I am a user of the Windows Subsystem for Linux (WSL), I might have noticed that when I plug in a USB flash drive, it doesn’t automatically appear in my Linux environment. Unlike my C: drive, which is typically mounted at /mnt/c, WSL does not automatically mount removable drives.

Fortunately, accessing my USB drive from within WSL is a straightforward process. This guide will walk through the two primary methods I use for mounting a USB drive in WSL2, from a simple drive letter mount to accessing the raw physical disk.

Understanding the Challenge: Why USB Drives Don’t Auto-Mount

WSL is designed to be a lightweight and isolated environment. For security and stability reasons, it does not automatically mount every device that is connected to my Windows host. This means I have to manually tell WSL to mount the drive.

Prerequisite: WSL2 is Recommended The methods described below work best with WSL2, which has a full Linux kernel and better support for hardware access. If I am still on WSL1, I should consider upgrading (wsl --set-version <DistroName> 2).

Method 1: The Easy Way (Mounting a Windows Drive Letter)

This is the simplest and most common method for accessing the files on a USB drive. It works by mounting the drive letter that Windows has assigned to the USB (e.g., E:).

Step 1: Identify the USB Drive Letter in Windows

First, I plugged in my USB drive and noted the drive letter that Windows assigned to it in File Explorer (e.g., E:).

Step 2: Mount the Drive in WSL

  1. I opened my WSL terminal (e.g., Ubuntu).
  2. Create a mount point. This is simply a directory where the contents of the USB will be accessible. 
    sudo mkdir /mnt/e
  3. Use the mount command to attach the Windows drive to the mount point. 
    sudo mount -t drvfs E: /mnt/e

Command Explanation:

  • sudo mount: The standard Linux command to mount a filesystem.
  • -t drvfs: Specifies the filesystem type as drvfs (Drive File System), which is the protocol WSL uses to communicate with the Windows filesystem.
  • E:: The Windows drive letter I want to mount.
  • /mnt/e: The destination directory (mount point) inside WSL.

Step 3: Access My Files

I can now access the files on my USB drive by navigating to the mount point. 

ls /mnt/e
cd /mnt/e

Method 2: The Advanced Way (Mounting a Raw Physical Disk)

For more advanced use cases, such as using Linux tools like dd, fdisk, or gparted, I may need to access the raw physical disk instead of just the formatted volume. The wsl --mount command allows me to do this.

Step 1: Identify the USB Disk in Windows

I opened PowerShell as an Administrator and listed all physical disks to find the disk number of my USB drive. 

Get-Disk

Example Output: 

Number Friendly Name  OperationalStatus Total Size Partition Style
------ -------------  ----------------- ---------- ---------------
0      NVMe SSD       Online            512 GB     GPT
1      USB DISK 3.0   Online            16 GB      MBR
In this example, the USB drive is Disk 1, which corresponds to the path \.\PHYSICALDRIVE1.

Step 2: Mount the Physical Disk into WSL

In the same administrative PowerShell terminal, use the wsl --mount command to attach the physical disk to WSL.

wsl --mount \\.\PHYSICALDRIVE1 --bare

The --bare flag attaches the physical disk without attempting to mount its filesystems.

Step 3: Identify and Mount the Partition in WSL

  1. Now, switch to your WSL terminal and list the block devices. 
    lsblk
    I should now see a new device, such as /dev/sdb, with its partitions (e.g., /dev/sdb1).
  2. Create a mount point and mount the partition. 
    sudo mkdir /mnt/usb
sudo mount /dev/sdb1 /mnt/usb

I can now access the files at /mnt/usb and use tools like fdisk /dev/sdb to interact with the raw disk.

How to Safely Unmount a USB Drive

Before I physically unplug my USB drive, I must unmount it to prevent data corruption.

For Method 1 (Drive Letter Mount): 

sudo umount /mnt/e

For Method 2 (Physical Disk Mount):

  1. Unmount the partition inside WSL: 
    sudo umount /mnt/usb
  2. Detach the physical disk from WSL in your PowerShell terminal: 
    wsl --unmount \\.\PHYSICALDRIVE1

Troubleshooting Common Issues

Issue Cause Fix
USB not showing in /mnt/ It’s not mounted yet. Use sudo mount -t drvfs E: /mnt/e.
wsl --mount gives an error I am not running PowerShell as an Administrator. Close and reopen PowerShell as an Administrator.
Cannot write to the USB The filesystem was mounted as read-only. For drvfs, I can try adding the -o metadata option to the mount command to better handle permissions.
WSL1 doesn’t show disks This is a limitation of WSL1. Upgrade my distribution to WSL2 with wsl --set-version <DistroName> 2.

Further Reading

If you’re encountering other issues with WSL, such as startup crashes, check out our troubleshooting guide:

Conclusion

Accessing USB drives in WSL2 is a simple process once I know the correct commands.

  • For quick and easy file access, mounting the Windows drive letter is the best approach.
  • For advanced tasks that require raw disk access, the wsl --mount command provides the power I need.

By following these steps, I can seamlessly integrate my USB storage into my WSL workflow, giving myself the best of both the Windows and Linux worlds.