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

Prerequisites

Before proceeding, make sure you:

• Have administrative access to the VM and the 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 the agent 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 the virtio-serial driver
   • Open Device Manager
   • Locate PCI Simple Communications Controller

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

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

Get-Service QEMU-GA

Ensure the service is running and is set to start automatically.

Verify Guest Agent Communication

Run on the Proxmox host:

qm agent \<vmid\> ping\

If configured correctly, the command returns a response without errors.

Best Practices

• Enable the 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
• Test the restore regularly.