https://ext4.wiki.kernel.org/index.php/Ext4_VM_Images does not
recommends to dd zero file and deletes it, but in case of enabling
discards and qcow2 image we can recreate qcow2 file with less used
space.
Also qemu-img able to enable compression for qcow2 files, that
sometimes may be useful because it natively supported by qemu.
Signed-off-by: Vasiliy Tolstov <v.tolstov@selfip.ru>
Vasiliy Tolstov