Windows 8.1 Qcow2 -

QCOW2 files only consume physical disk space as data is written, preventing a 60GB Windows installation from immediately taking up 60GB on the host.

Once loaded, your qcow2 disk will appear, and you can proceed with the installation. Performance Optimization Tips windows 8.1 qcow2

virt-install --name win8.1 --ram 4096 --vcpus 2 --disk path=win8.1.qcow2,format=qcow2,bus=virtio --cdrom /iso/win8.1.iso --cdrom /iso/virtio-win.iso --os-variant win8.1 --graphics spice --network network=default,model=virtio QCOW2 files only consume physical disk space as

In the world of enterprise virtualization and open-source cloud computing, few file formats carry as much weight as (QEMU Copy-On-Write version 2). It is the golden standard for disk images on platforms like QEMU, KVM (Kernel-based Virtual Machine), Proxmox VE, and even certain OpenStack deployments. Meanwhile, Windows 8.1 —despite reaching its end-of-life status—remains a popular lightweight guest operating system for legacy software testing, embedded systems, and low-resource virtual environments. It is the golden standard for disk images

Using QEMU command line (advanced):

qemu-img convert -f vhdx windows8.1.vhdx -O qcow2 windows8.1.qcow2