Create qcow2 with compat 1.1
Submitted by Chris Murphy
Currently gnome-boxes creates qcow2 with compat 0.10. The man page for qemu-img says compat 1.1 is now the default.
Is there a good reason to use compat 0.10 still? If not, switch to compat 1.1, it's more efficient. It's also what virt-manager is using by default.
"compat" Determines the qcow2 version to use. "compat=0.10" uses the traditional image format that can be read by any QEMU since 0.10. "compat=1.1" enables image format extensions that only QEMU 1.1 and newer understand (this is the default). Amongst others, this includes zero clusters, which allow efficient copy-on-read for sparse images.