Migrating just a couple of virtual machines from other virtualization platforms to KVM is easy. Virtualbox uses the Virtual Disk Image (.vdi) format. You can clone the vdi image to a RAW image format using vboxmanage. This way you will not alter your original virtual image file. Then QEMU provides the necessary tools to convert the RAW image to the qcow2 format. Qcow2 is QEMU’s Copy On Write image format.