How to Prepare a Proxmox VM for Backup

This guide explains how to prepare a virtual machine running on Proxmox VE for Backup. If you neew to perform MS SQL or Exchange backup, refer to the following KB article.

To properly prepare a Proxmox VM backup:

1. Install and enable QEMU Guest Agent
2. Adjust VSS mode (Windows) if other backup tools are used
3. Validate configuration and test backups

Prerequisites

Before proceeding, make sure you:

• Have administrative access to the VM and Proxmox host
• Use a supported backup solution

Refer to the following KB article for detailed information on the required permissions.

Step 1: Configure QEMU Guest Agent

What is QEMU Guest Agent?

The QEMU Guest Agent is a service installed inside the VM that enables communication between the host and guest OS.

It is required for:

• Graceful VM shutdown
• File system freeze/thaw during backups
• Application-consistent snapshots

Enable Guest Agent on the Host

After installing the agent inside the VM, enable it in Proxmox:

• GUI: VM → Options → Enable QEMU Guest Agent

• CLI:

qm set \<VMID\> \--agent 1

Install Guest Agent Inside the VM

Linux

Install using your package manager:

Debian/Ubuntu:

apt-get install qemu-guest-agent

RHEL/CentOS:

yum install qemu-guest-agent

Start and enable the service:

systemctl start qemu-guest-agent

systemctl enable qemu-guest-agent

Windows

1. Download and attach the VirtIO ISO
2. Install virtio-serial driver
   • Open Device Manager
   • Locate PCI Simple Communications Controller

Update driver from ISO: \vioserial\<OSVERSION>\

3. Install Guest Agent:
   • Open ISO → guest-agent folder
   • Run:
     • qemu-ga-x86_64.msi (64-bit)
     • or qemu-ga-i386.msi (32-bit)
4. Verify service:

Get-Service QEMU-GA

Ensure the service is running and set to start automatically.

Verify Guest Agent Communication

Run on Proxmox host:

qm agent \<vmid\> ping\

If configured correctly, the command returns without errors.

Best Practices

• Enable QEMU Guest Agent. If you plan do not use it by some reason, disable it in the VM options (in this case the backup cannot be application - consistent)
• Avoid running another backup solutions with conflicting VSS modes
• Refer to the following [KB article] if you intend to back up Proxmox VM or create an Image-Based Backup
• Test restore regularly