Migrating virtual machines from VMware ESXi to Proxmox VE is becoming increasingly popular as organizations look for a cost-effective, enterprise-grade virtualization platform without the high licensing costs associated with VMware.

One question we hear from customers almost every week is:

“Do I really need to install VirtIO drivers after migrating my Windows VMs to Proxmox?”

The short answer is yes—but not immediately.

In this article, we’ll explain why VirtIO drivers are important, why you shouldn’t rush to install them during the migration, and the safest method for upgrading your Windows virtual machines after a successful migration.

Why Windows VMs Continue to Work Without VirtIO Drivers

When migrating a Windows virtual machine from VMware ESXi to Proxmox VE, the VM is usually configured to use hardware that Windows already recognizes.

For example:

• LSI Logic SAS storage controller
• SATA controller
• Intel E1000 network adapter

Because Windows already includes drivers for these devices, the virtual machine boots normally after migration without requiring any additional software.

This allows administrators to complete the migration with minimal risk and downtime.

However, while the VM works perfectly, it is not yet optimized for Proxmox VE.

What Are VirtIO Drivers?

VirtIO is a paravirtualized driver framework designed specifically for KVM-based hypervisors such as Proxmox VE.

Instead of emulating physical hardware like VMware does, VirtIO allows Windows to communicate directly with the virtual hardware using highly optimized drivers.

These drivers are maintained by the KVM community and Red Hat and are considered the standard for Windows guests running on Proxmox.

Benefits of Installing VirtIO Drivers

Installing VirtIO drivers provides several advantages.

Improved Disk Performance

VirtIO SCSI delivers:

• Higher IOPS
• Lower latency
• Reduced CPU utilization
• Better throughput under heavy workloads

This becomes particularly noticeable on:

• SQL Server
• Microsoft Exchange
• File servers
• Backup servers
• High-I/O application servers

Better Network Performance

The VirtIO network adapter provides:

• Higher throughput
• Lower CPU overhead
• Lower latency
• Better scalability for busy application servers

Compared to the legacy Intel E1000 adapter, VirtIO is significantly more efficient.

Reduced CPU Usage

Because VirtIO avoids emulating traditional hardware, fewer CPU cycles are required to process disk and network operations.

This allows more CPU resources to be used by the applications running inside the VM.

Better Integration with Proxmox

VirtIO drivers work together with the QEMU Guest Agent to provide features including:

• Graceful shutdown
• Guest reboot
• IP address reporting
• Improved backup consistency
• File system freeze/thaw during backups
• Better monitoring

Should You Install VirtIO Drivers Before or After Migration?

This is where many administrators make a mistake.

Although it is technically possible to install VirtIO drivers before migration, we generally recommend installing them after the VM has been successfully migrated and validated.

Why?

Because migration projects involve enough variables already:

• Storage migration
• Network migration
• Hardware compatibility
• Application validation
• DNS changes
• Production cutover

Adding storage controller changes during the migration increases the risk unnecessarily.

Our preferred production approach is:

1. Migrate the VM.
2. Confirm Windows boots successfully.
3. Verify applications and services.
4. Install VirtIO drivers.
5. Switch to VirtIO hardware during a planned maintenance window.

This separates migration risk from optimization work.

Is Installing VirtIO Drivers Mandatory?

No.

A Windows VM can continue running perfectly using:

• LSI Logic SAS
• SATA
• Intel E1000

Many organizations do exactly this immediately after migration.

However, if your goal is to obtain the best performance from Proxmox VE, VirtIO drivers should be installed as part of your post-migration optimization process.

Safe Procedure for Installing VirtIO Drivers

Step 1 – Mount the VirtIO Driver ISO

In Proxmox VE:

• Open the virtual machine.
• Navigate to Hardware.
• Attach the latest virtio-win.iso to the CD/DVD drive.

Step 2 – Install the Guest Tools

Inside Windows, open the mounted CD and run:

virtio-win-guest-tools.exe

This installer includes:

• VirtIO storage drivers
• VirtIO network drivers
• Balloon driver
• QEMU Guest Agent
• Additional supporting drivers

After installation, reboot the virtual machine.

Step 3 – Verify Driver Installation

Open Device Manager and verify that the VirtIO drivers are present.

At this point, the drivers are installed but Windows is still using the original storage controller and network adapter.

Safely Switching the Network Adapter

Changing the network adapter is straightforward.

1. Shut down the VM.
2. In Proxmox, replace the E1000 adapter with a VirtIO network adapter.
3. Start the VM.
4. Windows automatically detects the new adapter.
5. Reconfigure the IP address if necessary.

Because the driver has already been installed, this process is generally low risk.

Safely Switching the Storage Controller

The storage controller requires more care.

Changing directly from LSI Logic SAS to VirtIO SCSI without the proper driver loaded can result in a Windows boot failure.

The safest approach is:

1. Install the VirtIO drivers.
2. Add a temporary small VirtIO disk (1 GB is sufficient).
3. Boot Windows.
4. Windows detects and initializes the VirtIO SCSI controller.
5. Shut down the VM.
6. Remove the temporary disk.
7. Change the boot disk to VirtIO SCSI.
8. Boot the VM normally.

This ensures Windows has already loaded the correct storage driver before the boot disk depends on it.

What About VMware Tools?

VMware Tools are no longer required once the VM is running on Proxmox.

However, we recommend leaving VMware Tools installed during the initial migration.

After:

• Windows boots successfully
• Applications are verified
• VirtIO drivers are installed
• QEMU Guest Agent is functioning

you can safely uninstall VMware Tools.

Keeping VMware Tools during the migration provides an easier rollback if the VM needs to be powered back on in VMware.

Recommended Migration Workflow

For production Windows Server migrations, our recommended workflow is:

1. Shut down the VMware VM.
2. Migrate the VM to Proxmox VE.
3. Boot and validate Windows.
4. Verify all applications and services.
5. Install VirtIO Guest Tools.
6. Reboot.
7. Replace the network adapter with VirtIO.
8. Test networking.
9. Migrate the storage controller to VirtIO SCSI during a maintenance window.
10. Verify performance.
11. Remove VMware Tools.
12. Install and verify the QEMU Guest Agent.

This phased approach minimizes downtime while reducing the risk of boot failures.

Final Thoughts

Migrating from VMware to Proxmox VE is more than simply copying virtual disks. To get the best long-term performance, Windows virtual machines should eventually use VirtIO drivers instead of legacy emulated hardware.

That said, optimization should never come at the expense of stability.

By separating the migration from the optimization phase, organizations can significantly reduce project risk while still achieving the performance benefits that make Proxmox VE such an attractive virtualization platform.

If you’re planning a VMware-to-Proxmox migration and want to ensure minimal downtime with a structured migration methodology, our team can help design and execute a migration plan tailored to your environment.