Can i shrink the image file size?

John Wong
2009-03-21T17:34:16Z

I create the 30G qcow2 image file, installed winxp, winxp show me the
harddisk used 5G, but the image file size is 12G now.
can i shrink the image file size? how?
my kvm version is: "kvm-84", qemu version is: "0.9.1".
please help, thank you.