$ tar tf openswitch-appliance-image-appliance-ops-0.4.0-master+2016080600.ova
 OpenSwitch.ovf
 OpenSwitch.vmdk
 $ tar xf openswitch-appliance-image-appliance-ops-0.4.0-master+2016080600.ova
 $ ls OpenSwitch.*
 OpenSwitch.ovf OpenSwitch.vmdk
 $ qemu-img convert -f vmdk -O raw OpenSwitch.vmdk OpenSwitch.img
 $ ls OpenSwitch.*
 OpenSwitch.img OpenSwitch.ovf OpenSwitch.vmdk