On the host, add discard=unmap to the drive option: -drive file=win8.qcow2,format=qcow2,if=virtio,discard=unmap
: Complete the standard Windows setup wizard inside the virtual machine. 2. Convert an Existing Windows Drive to QCOW2 windows 8 qcow2
Getting Windows 8 to run smoothly inside a QCOW2 container is not a "plug-and-play" experience. It is a rite of passage for system administrators. On the host, add discard=unmap to the drive
qemu-system-x86_64 \ -enable-kvm \ -cpu host \ -smp 4 \ -m 4096 \ -drive file=win8.qcow2,format=qcow2,if=virtio \ -drive file=Win8_ISO.iso,media=cdrom \ -drive file=virtio-win.iso,media=cdrom \ -netdev user,id=net0 \ -device virtio-net-pci,netdev=net0 \ -vga qxl \ -display spice-app On the host
The -c flag enables compression, often reducing a 15GB image to 8GB.