From Fedora Project Wiki
One of the improvements involved changing the cluster size from 4K to 64K. There is a need for a GUI tool to analyse images, suggest converting them to the new format, and carry out the conversion.
Did this feature land? I just tried some qcow2 guests here and while everything looks ok, once i do a high i/o activity in the guest (a mockbuild) the guest stops responding to pings, is not responsive on command line and in general stops. After the mockbuild finally finishes things go back to normal. raw format doesn't seem to have this issue. Additionally, I can find no changelog or other entries about this landing upstream or the version reffered to in the page existing. -- user:kevin