Convert qcow2 to raw format

This guide is for existing VM’s.

Backup VM config

virsh dumpxml <vmname> > ~/vmname.xml

Replace vmname with Virtual Machine (Domain) name. You can find correct name by running virsh list --all

Image Conversion

Find path of existing image (in qcow2) format

virsh dumpxml <vmname> | grep file

Will show something like:

    <disk type='file' device='disk'>
      <source file='/var/lib/libvirt/images/ubuntu-kvm/tmpjaAefX.qcow2'/>

Conversion

Sample command is:

qemu-img convert {image_name}.qcow2 {image_name}.raw

So in this case, it will be:

qemu-img convert /var/lib/libvirt/images/ubuntu-kvm/tmpjaAefX.qcow2 /var/lib/libvirt/images/ubuntu-kvm/tmpjaAefX.raw

At this point conversion is complete.

Edit VM Configuration

Edit VM Config

Run following command to open editor.

virsh edit <vmname>

Find lines like below:

    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/ubuntu-kvm/tmpU2z98r.qcow2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>

Replaceqcow2 withraw Ain 2 places highlighted above.

Your update config will look like below:

    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/ubuntu-kvm/tmpU2z98r.raw'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </disk>

Save your changes and exit editor.

Start VM

Run following command:

virsh start <vmname>

At this point you can run your disk I/O benchmarks again to check speed.