Skip to content

Run Proxmox Backup Server as a VM with Disk Passthrough

Use at your own risk. All guides and scripts are provided for educational purposes only. Always review and understand any code before running it — especially with administrative privileges. Test in a safe environment before using in production. Your system, your responsibility.

Running Proxmox Backup Server (PBS) as a VM on the same Proxmox VE host is a practical and cost-effective setup for home labs. Instead of dedicating a separate machine to backups, you pass a physical disk directly through to the PBS VM — giving it exclusive, direct access to the backup storage.

This guide covers the full setup on Proxmox VE 9.x.

Requirements

  • Proxmox VE 9.x
  • A dedicated physical disk for backup storage (separate from your OS disk)
  • PBS ISO downloaded from proxmox.com/downloads
Never use your Proxmox OS disk for passthrough. The disk you pass through to the PBS VM must be a dedicated, separate disk. Passing through the wrong disk will cause data loss.

Step 1 – Find the Disk ID

Disk passthrough in Proxmox is done using the disk’s persistent ID, not /dev/sdb — device names can change after a reboot.

SSH into your Proxmox host and list disks by ID:

ls -l /dev/disk/by-id/

Find your backup disk. It will look something like:

ata-WDC_WD4000FYYZ_WD-XXXXX -> ../../sdb

Note the full ID path — you’ll need it in Step 4. Ignore entries ending in -part1, -part2 etc. (those are partitions).

Step 2 – Create the PBS Virtual Machine

  1. In the Proxmox web interface, click “Create VM”
  2. General – give it a name (e.g. pbs) and a VM ID
  3. OS – select your PBS ISO, set OS type to Linux, kernel 6.x
  4. System – leave defaults, optionally enable Qemu Agent
  5. Disks – create a small boot disk (32 GB is enough for the PBS OS)
    • Set Bus/Device to VirtIO Block
  6. CPU – 2 cores, type Host
  7. Memory – 4096 MB (4 GB) minimum, 8 GB recommended
  8. Network – connect to your main bridge (e.g. vmbr0)
  9. Confirm – click Finish

Step 3 – Add Disk Passthrough via Command Line

Disk passthrough must be configured from the Proxmox host shell — it cannot be done through the web UI.

SSH into your Proxmox host and run (replace the disk ID and VM ID with your own):

qm set 100 --scsi1 /dev/disk/by-id/ata-WDC_WD4000FYYZ_WD-XXXXX
  • 100 = your VM ID
  • --scsi1 = the next available SCSI slot (use scsi1 if scsi0 is your boot disk)
  • The disk ID path from Step 1

Verify it was added correctly:

qm config 100

You should see your passthrough disk listed under scsi1.

Step 4 – Install Proxmox Backup Server

  1. Start the VM and open the console
  2. Boot from the PBS ISO
  3. Follow the installer — set hostname (e.g. pbs.local), IP address, and password
  4. Complete the installation and reboot
  5. Remove the ISO from the VM hardware after installation

Access the PBS web interface at:

https://your-pbs-ip:8007

Log in with root and the password you set during installation.

Step 5 – Initialize the Backup Disk in PBS

  1. In the PBS web interface, go to Administration → Disks
  2. Your passthrough disk should appear in the list
  3. Select it and click “Initialize Disk with GPT”
  4. Go to Administration → Disks → Directory
  5. Click “Create: Directory”
    • Select your disk
    • Choose filesystem: ext4 (recommended for single disk)
    • Set a name for the datastore (e.g. backup-store)
  6. Click Create

Step 6 – Add PBS as a Storage Backend in Proxmox VE

  1. In Proxmox VE, go to Datacenter → Storage → Add → Proxmox Backup Server
  2. Fill in:
    • ID: pbs (or any name)
    • Server: IP address of your PBS VM
    • Username: root@pam
    • Password: your PBS root password
    • Datastore: the name you created in Step 5
  3. Click Add

PBS is now available as a backup target for all your VMs.

Step 7 – Configure a Backup Job

  1. In Proxmox VE, go to Datacenter → Backup → Add
  2. Select:
    • Storage: your PBS storage
    • Schedule: daily, weekly, or custom
    • VMs: select which VMs to back up
    • Mode: Snapshot (recommended)
  3. Click Create

Your VMs will now be backed up automatically to the dedicated disk in your PBS VM.

Tips

  • Set a pruning schedule in PBS to automatically remove old backups and manage disk space
  • PBS supports deduplication and compression out of the box — backup storage usage is much lower than raw VM sizes
  • You can access backup logs and verify backup integrity directly in the PBS web interface

Related Links