Clone disk to raw/qcow2

#Copy disk
dd if=/dev/sda of=hdd.raw bs=4M
#Convert to qcow2
qemu-img convert -f raw -O qcow2 hdd.raw hdd.qcow2
#Shrinking
qemu-img convert -c -O qcow2 hdd.qcow2 hdd-shrunk.qcow2

A note on sizes:

1. Original disk: 160 GB
2. Raw image file: 150 BG
3. First qcow2 image: 144 GB
4. After shrinking: 118 GB

Links

conversion, shrinking