Building a highly optimized Windows 10 QCOW2 image requires standard installation media and Red Hat's VirtIO drivers. Without VirtIO drivers, KVM cannot recognize the virtual disk or network interface during the setup process. Prerequisites A Linux host with KVM/QEMU installed. Official Windows 10 Installation ISO.
qemu-img convert -O qcow2 -c windows10.qcow2 compressed_win10.qcow2 Use code with caution. Expanding Storage Space
qemu-img convert -f vmdk -O qcow2 windows10.vmdk windows10.qcow2 windows 10qcow2
However, the true power of the QCOW2 format lies in its namesake feature: Copy On Write (COW). This functionality allows for highly efficient snapshot capabilities. In a professional or development environment, the ability to save the state of a machine instantly and revert to it later is invaluable. If a user wishes to test a potentially unstable software application or a system update on Windows 10, they can take a snapshot of the QCOW2 image. The format handles this by freezing the original data and writing any subsequent changes to a new layer. If the test goes wrong, the user simply discards the new layer, instantly reverting the Windows 10 environment to its pristine state. This non-destructive workflow makes QCOW2 images the preferred choice for developers and system administrators who require a safe sandbox to test configurations on Windows without the risk of requiring a full OS reinstallation.
The block storage drivers that allow Windows to see and communicate with the QCOW2 disk. Building a highly optimized Windows 10 QCOW2 image
A 100 GB virtual disk only occupies the space of the actual files written (typically 15–20 GB initially for a fresh Windows 10 install).
Compress your base images to save host disk space or ease file transfers. Step 1: Preparing the Prerequisites Official Windows 10 Installation ISO
qemu-img create -f qcow2 win10.qcow2 60G
This installs the core QEMU engine, the qemu-img utility for managing disk images, and virt-manager , a user-friendly graphical interface for managing VMs.
Ensure that the discard option is enabled in the disk configuration and that you run a scheduled optimization trim inside the Windows 10 defragmentation app. Final Thoughts
Download the latest installation media from the Microsoft Software Download Page.