qemu-img convert -f raw -O qcow2 -c windows7.raw windows7.qcow2
Performance tip after conversion: Run qemu-img check -r all windows7.qcow2 to repair any inconsistencies from foreign formats. Also, consider qemu-img deflate windows7.qcow2 after heavy use to reclaim sparse space.
A QCOW2 file is a disk image format used by QEMU, KVM, and other virtualization platforms. Using Windows 7 on a QCOW2 image allows you to run this legacy OS in a virtual machine (VM) with features like snapshots, compression, and thin provisioning. windows 7qcow2
Create snapshot:
qemu-img snapshot -c before_update win7.qcow2
List snapshots:
qemu-img snapshot -l win7.qcow2
Revert to snapshot:
qemu-img snapshot -a before_update win7.qcow2