We had experience that if we clone vm from snapshot with sprase raw disk in file domains, the process would get very slow if the disk defined virtual size is big but actual size is small, so i popose the frontend UI to be able to add caw disk in file domains.

And I'm happy to implement it. I want to know if there is any problem with my theory, I'm not so experienced in storage. And I created a more detailed expanation to address this problem: https://bugzilla.redhat.com/show_bug.cgi?id=1117219

thanks.