You can save the exact state of your Windows 10 VM at a point in time. If Windows crashes or gets infected with malware, you can instantly revert to that saved "checkpoint". Copy-on-Write (CoW):
This allows for "linked clones," where multiple VMs can share the same base "golden image" of Windows 10 while only saving unique changes to their own separate files. Compression & Encryption:
qemu-img convert -p -f vmdk -O qcow2 existing_windows10.vmdk win10_from_vmware.qcow2
This guide outlines how to use the Windows 10.qcow2 file. Since .qcow2 is the disk image format for (Quick Emulator), this file is typically a virtual hard drive containing a Windows 10 installation. Windows 10.qcow2
In Virt-manager or UTM, select "Import existing disk image" instead of "Install from CD/DVD".
The "Copy-On-Write" nature means the file only takes up as much space as the data actually written to it, even if the virtual disk is set to a larger size (e.g., a 60GB disk might only be a 15GB file).
Have a base Windows10-base.qcow2 (never write to it). Create child images: You can save the exact state of your
Windows 10 is notoriously resource-heavy inside virtualized environments. To eliminate lag and maximize disk I/O performance, apply these optimizations on your hypervisor or Proxmox/Virt-Manager settings. 1. Optimize Disk Cache Settings
Windows 10 is designed for bare-metal hardware. Running it efficiently within a QCOW2 container requires specific performance tuning:
After Windows 10 boots successfully, the VirtIO drivers must be properly installed for the rest of the hardware (network, ballooning, etc.). Insert the VirtIO driver CD by right-clicking on the ISO file in the VM's virtual drive and selecting "Eject". Then, attach the virtio-win.iso file again. Windows should automatically install most drivers, but it is recommended to manually run the installer from the CD-ROM to ensure everything is installed. Compression & Encryption: qemu-img convert -p -f vmdk
Because QCOW2 uses Copy-On-Write, these operations take seconds and save the entire memory and disk state.
When the Windows 10 installer reaches the disk selection screen, it will appear completely empty. This happens because Windows does not natively include the VirtIO SCSI controller drivers. Click .