Passthrough Physical Disk to Proxmox VMs

Introduction

Passing a physical disk directly to a virtual machine in Proxmox can improve performance and simplify storage management. This guide explains how to locate the disk, assign it to a VM, and detach it if needed.

1. Locate and Prepare the Disk

Identify the Disk

• In the Proxmox UI, go to Disks.
• Find your disk and note the serial number.
• (Optional) Wipe the disk if you want to erase all data.

Get Disk Path

Run this command in the Proxmox shell to list disks by ID:

find /dev/disk/by-id/ -type l | xargs -I{} ls -l {} | grep -v -E '[0-9]$' | sort -k11 | cut -d' ' -f9,10,11,12

Locate the path corresponding to your disk (e.g., /dev/disk/by-id/ata-WDC...).

2. Assign Disk to VM

Add Disk via Shell

Use the qm command to attach the disk:

qm set <vmid> -<disk-type><number> /dev/disk/by-id/<disk-serial>

• Replace <vmid> with your VM ID (e.g., 100).

• Use scsi or virtio depending on the guest OS.

  • scsi is recommended for Linux and Windows.
  • virtio may be better for macOS guests.

Example:

qm set 100 -scsi1 /dev/disk/by-id/ata-WDC...

Confirm and Boot

• In the VM’s Hardware tab, the disk should now appear.
• Start the VM and check if the disk is detected.

3. Remove Disk from VM

To detach the disk from the VM, use:

qm unlink <vmid> --idlist <disk-type><number>

Example:

qm unlink 100 --idlist scsi1

This will unlink the passthrough disk without affecting the VM configuration.

Conclusion

Using a physical disk passthrough in Proxmox allows your VM to access storage with near-native performance. This is useful for dedicated drives, testing, or improving I/O. You can attach and remove disks easily using the qm CLI and Proxmox UI.