Windows on a VM

Windows is one of the most popular guest operating systems for Unraid users, especially for gaming, productivity, and support for legacy applications. Here are essential considerations for running Windows VM.

Before you begin

• Microsoft ended support for Windows 7 in Jan. 2020, Windows 8.1 in January 2023, and Windows 10 in October 2025. Use Windows 11 (or later) or Server 2022 (or later) for ongoing security updates.
• Always test VM stability before activating your Windows license.
• For GPU passthrough, use OVMF (UEFI) BIOS with Windows 11 or newer.

Supported configurations

Windows edition	Recommended BIOS	Machine type	Notes
Windows 11	OVMF TPM	Q35	Requires TPM 2.0 emulation
Windows Server 2022	OVMF	Q35	Ideal for enterprise workloads
Windows 10	OVMF	Q35	Deprecated (EOL Oct 2025)
Windows Server 2019	OVMF	i440fx/Q35	Compatible but not recommended

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VirtIO driver management

Windows requires paravirtualized drivers for optimal performance with Unraid’s virtualization stack.

To install or update drivers:

Automatic installation

1. In Settings → VM Manager, set a default VirtIO ISO path (e.g., /mnt/user/isos/virtio-win.iso).
2. When creating a Windows VM, the ISO will auto-attach as a virtual CD-ROM.
3. During Windows setup, load drivers from the VirtIO ISO when prompted for storage controllers.

Manual update

1. Download the latest stable VirtIO drivers ISO and save it to your Unraid isos share.

   Verify download integrity

   Download the CHECKSUM file from the same directory to verify the ISO's integrity. This helps ensure your download is complete and hasn't been tampered with.

:::

2. Edit your VM settings to point to the new ISO in the isos share.

3. In Windows Device Manager:

   • Right-click devices with yellow warnings
   • Select Update driver → Browse my computer
   • Navigate to the VirtIO ISO drive (usually D:\ or E:\)

4. Reboot after updating all drivers.

tip

Using Unraid 7 or later, you can automatically inject VirtIO drivers during the Windows installation. Enable this in VM Settings → Advanced Options.

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Setting up hibernation

Hibernation lets you save your entire Windows VM state - including open applications and documents - to disk. This allows you to power off the VM without losing any work. When you resume, Windows restores everything exactly as you left it, skipping the normal boot process. This feature is handy when you need to reboot or power down your Unraid host or want to save energy while keeping your VM's state intact.

Benefits of hibernation

• Save energy by powering down idle VM without losing progress
• Quickly resume work after host maintenance or updates
• Reduce wear on SSDs compared to frequent complete shutdowns and reboots

To use hibernation reliably, you must install the QEMU Guest Agent in your Windows VM. This agent allows Unraid to communicate with the VM for advanced operations like hibernation, shutdown, and live statistics reporting.

How to install the QEMU Guest Agent - Click to expand/collapse

1. Start your Windows VM with the VirtIO drivers ISO mounted.
2. Open File Explorer and navigate to the VirtIO drivers media.
3. Open the guest-agent folder.
4. Run qemu-ga-x64.msi to install the agent. (You may briefly see a command box; no confirmation dialog will appear.)

How to enable hibernation in Windows - Click to expand/collapse

1. Open Control Panel and search for Power Options.
2. Click on Choose what the power buttons do.
3. Click Change settings that are currently unavailable to unlock shutdown settings.
4. Check the Hibernate option.
5. Click Save changes.

The Hibernate option will now appear in the Windows Power menu.

What if hibernation fails?

If your VM fails to hibernate or resume properly, you may lose unsaved work or face a failed restore. Always save important data before hibernating. If issues persist, ensure the QEMU Guest Agent is installed and updated, and check the Windows event log for errors.

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Performance tuning

Optimizing your Windows VM can improve responsiveness, reduce disk usage, and avoid common issues with device passthrough or shutdown. These adjustments are optional and can be applied as needed.

Disable fast startup

Disabling fast startup can help prevent issues with device passthrough. It ensures your VM hardware initializes correctly every time it boots. While this setting is designed for physical PCs, in a virtual environment, it can often cause more problems than benefits.

How to disable Fast Startup - Click to expand/collapse

1. Open Control Panel and search for Power.
2. Click on Choose what the power buttons do.
3. Click Change settings that are currently unavailable.
4. Uncheck Turn on fast startup under Shutdown settings.
5. Click Save changes.

Disable hiberfil.sys

Hibernation in Windows creates a large hidden file called hiberfil.sys. This file can consume significant disk space and increase disk activity in your VM. If you don't rely on hibernation, disabling it will free up storage and reduce unnecessary I/O activity.

How to disable hibernation and remove hiberfil.sys - Click to expand/collapse

1. Right-click the Start button and select Windows Terminal (Admin) or Command Prompt (Admin).
2. Type: powercfg /h off
3. Press Enter and reboot your VM. The hiberfil.sys file will be removed from your C:\ drive.

Disable Windows indexing

Windows Search indexing continuously scans your virtual machine's storage to catalog files for faster search results. However, on a virtual machine, this can cause unnecessary disk I/O, slow down performance, and increase wear on your physical storage, especially SSDs in your cache pool.

How to disable Windows indexing - Click to expand/collapse

1. Press Windows + R to open the Run dialog, type services.msc, and press Enter.
2. In the Services window, scroll down and right-click Windows Search, then select Stop.
3. Double-click Windows Search, change Startup type to Disabled, and click OK.

Disable automatic disk defragmenting

Windows is designed to defrag physical hard drives on a regular schedule automatically. On a VM - especially when using SSD storage or thin-provisioned vDisks - automatic defragmenting is unnecessary and can also reduce disk lifespan and degrade performance.

How to disable automatic disk defragmenting - Click to expand/collapse

1. Open File Explorer, right-click the C: drive, and select Properties.
2. Go to the Tools tab and click Optimize.
3. Click Change settings.
4. Uncheck Run on a schedule and click OK.

Enable high-performance power mode

Power management features in Windows are designed for laptops and desktops to save energy. In a VM environment, these features can unnecessarily throttle performance or suspend your VM, making it less responsive and harder to manage.

Enabling High Performance mode ensures your VM always runs at full speed and is less likely to pause or suspend unexpectedly.

How to enable high performance power mode - Click to expand/collapse

1. Open Control Panel and search for "power."
2. Click Choose a power plan.
3. Select High performance under Preferred plans.

Enable remote desktop access

Remote desktop protocol (RDP) allows you to access your Windows VM from another device. It offers better performance and compatibility compared to VNC. Note that RDP is supported only on Windows Professional and Enterprise editions. Also, your Windows user account must have a password set.

caution

RDP is not available on Windows Home editions. Always set a secure password for your Windows user account before enabling RDP.

How to enable remote desktop (RDP) access - Click to expand/collapse

To enable RDP access, follow these steps:

1. Press Windows + I to open Settings, then navigate to System → About and click Advanced system settings.
2. In the System Properties window, click the Remote tab, then select Enable Remote Desktop.
3. Click OK to confirm the changes.
4. From your client device, use a Microsoft RDP client to connect to the IP address of the VM (not the Unraid server).

tip

Official Microsoft RDP clients are available for Windows, Mac, Android, and iOS. Make sure your VM is on a network bridge that allows LAN access.

Fix HDMI audio with MSI interrupts

If you're having trouble with HDMI audio in a Windows VM that uses GPU passthrough (which often occurs with NVIDIA graphics cards), enabling Message Signaled Interrupts (MSI) might help. MSI enhances the way interrupts are managed for passed-through devices.

How to enable MSI interrupts - Click to expand/collapse

caution

Back up your VM before making any registry changes. Incorrect modifications can cause system instability.

1. Verify MSI capability:

   • Start your VM with GPU passthrough enabled.
   • Access Unraid via WebTerminal or SSH.
   • Run the command lspci -v -s 01:00.0 (replace 01:00.0 with your GPU's PCI address).
   • Look for the line: Capabilities: [68] MSI: Enable+ Count=1/1 Maskable- 64bit+.

2. Enable MSI in Windows:

   • If MSI shows Enable-, follow Microsoft's guide or use the MSI Mode Utility to modify your Windows registry settings.
   • Reboot the VM after making the changes.

For more technical details, see VFIO interrupts explained.

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Upgrading to Windows 11

Windows 11 requires TPM 2.0 and Secure Boot. Unraid's OVMF-TPM BIOS provides the virtual TPM support needed for these requirements.

Before upgrading

• Create a complete backup of your VM.
• Ensure that Unraid is running version 6.10 or later.
• Verify that your Windows 10 VM meets the Windows 11 system requirements.

To add TPM support:

1. Shut down your Windows 10 VM.
2. Edit the VM settings.
3. Change BIOS from OVMF to OVMF-TPM.
4. Save the changes and start the VM.

Upgrade methods

In-place upgrade

1. Download the Windows 11 Installation Assistant.
2. Run the installer and follow the on-screen instructions.
3. Reboot when prompted.

Clean install

1. Download the Windows 11 ISO.
2. Upload the ISO to your isos share on your Unraid server.
3. Modify your VM template to boot from the ISO in the isos share.
4. Boot the VM from the ISO and perform the fresh installation.
5. Reinstall your applications and restore your data from backup.

Expanding Windows VM vDisk partitions

Data loss risk

Expanding or modifying vDisk and partition layouts can lead to irreversible data loss if not done carefully. Always create a full backup or snapshot of your VM before proceeding.

After you expand your vDisk following the steps in Expand a vDisk, you may encounter an issue where Windows’ default recovery partition blocks you from easily expanding your system (C:) partition to utilize the new space. To resolve this issue, you need to delete the recovery partition and then use Windows Disk Management to expand the partition.

After you complete the initial vDisk expansion:

1. Start your Windows VM.
2. Open command prompt: Press the Windows key, type cmd, and hit Enter.
3. Launch diskpart: Type diskpart and press Enter.
4. List disks: Type list disk and press Enter.
5. Select the expanded disk: Type select disk #, replacing # with the correct disk number.
6. List partitions: Type list partition and press Enter.
7. Identify the recovery partition: Look for the recovery partition that comes after your primary partition.
8. Select and delete the recovery partition:
   • Type select partition #, replacing # with the number of the recovery partition.
   • Type delete partition override and press Enter.
9. Expand the C: partition:
   • Right-click the Start menu and select Disk Management.
   • Right-click the partition you want to extend (usually C:) and choose Extend Volume....
   • Follow the prompts to use the unallocated space.

tip

You only need to remove the recovery partition if it blocks access to adjacent free space. If the unallocated space is already next to your C: partition, you can extend it without deleting anything.

warning

Changes made to disk partitions are permanent and cannot be undone. Ensure that your data is securely backed up before deleting any partitions.