Windows 10qcow2 Page

Prepared by: Virtualization Engineering Team
Appendices available upon request: Sample libvirt domain XML for Windows 10 QCOW2, PowerShell optimization script.

To develop a Windows 10 QCOW2 image, you typically use QEMU/KVM to create a virtual disk and install the OS from an ISO. This format is widely used in cloud environments (like OpenStack) and Linux-based virtualization (like Proxmox or Virt-Manager). 1. Create the QCOW2 Virtual Disk First, use the

tool to create a blank virtual disk file. You should allocate at least 40GB to 50GB for a standard Windows 10 installation. DEV Community qemu-img create -f qcow2 windows10.qcow2 Use code with caution. Copied to clipboard 2. Download Essential Components Windows 10 ISO : Use the official Microsoft Media Creation Tool to download the latest ISO. VirtIO Drivers

: To ensure high performance and proper disk recognition during installation, download the Windows VirtIO Drivers ISO

. Without these, the Windows installer might not see your QCOW2 disk. OpenNebula 3. Launch the Installation

Run the following QEMU command to start the installation. This command mounts both the Windows ISO and the VirtIO driver disc: Yandex Cloud qemu-system-x86_64 -m windows 10qcow2

G -cpu host -enable-kvm \ -drive file=windows10.qcow2,if=virtio \ -cdrom /path/to/windows10.iso \ -drive file=/path/to/virtio-win.iso,media=cdrom \ -net nic,model=virtio -net user \ -vga virtio -boot d Use code with caution. Copied to clipboard 4. Install Windows and Drivers Load Drivers

: When the installer asks "Where do you want to install Windows?", the list will likely be empty. Click Load Driver and browse the VirtIO CD (usually the folder for your architecture) to reveal the QCOW2 disk. Post-Install

: Once Windows boots, open the VirtIO CD in File Explorer and run the virtio-win-guest-tools.exe

to install all remaining drivers for networking and performance. OpenNebula 5. Optimization & Image Prep (Optional) How to create Windows VM? - OpenNebula Forum

Problem: The VM feels slow, and disk is at 100% usage. Fix: You forgot the VirtIO drivers. Switch the disk bus from IDE to VirtIO in your VM config. Effect of caching modes (none, writeback, writethrough), AIO

Problem: The QCOW2 file is huge even though the guest shows free space. Fix: Windows 10 doesn't TRIM automatically on some QEMU versions. Run the PowerShell Optimize-Volume command weekly.

Problem: qemu-img convert is too slow. Fix: Add -W (write caching) and use -p to show progress: qemu-img convert -p -W -f qcow2 -O raw ...

You will boot from the ISO and install onto the qcow2 disk.

Using virt-install (command line):

virt-install --name win10 --ram 4096 --vcpus 4 \
--disk path=/path/to/windows10.qcow2,format=qcow2 \
--cdrom /path/to/Windows10.iso \
--os-variant win10 --graphics spice

Using virt-manager (GUI):

Important: During Windows setup, if the disk is not detected, you need VirtIO drivers. Load them by adding a second CD-ROM with the latest VirtIO ISO (from Fedora’s repo).

Using virsh or qemu-img:

virsh snapshot-create-as win10 --name "before-update" --disk-only --atomic

Or using QEMU:

qemu-img snapshot -c pre_patch windows10.qcow2
qemu-img snapshot -l windows10.qcow2   # List snapshots

Qcow2 (QEMU Copy-On-Write version 2) is a flexible, sparse file format. It grows as data is written, supports snapshots, compression, and encryption. For Windows 10, it’s a popular choice due to storage efficiency and snapshot capabilities.