This change affects the method by which snapshots are deleted. Previously, deleting a snapshot was not as easy as might be expected, and involved creating a temporary space equivalent to the full size of the disk (even for thinly provisioned disks). With this change, this process has been greatly simplified.
This bug is somewhat tricky and will involve updating the section of the Technical Guide that talks about snapshot deletion. It might also involve looking into the sections of the Administration Guide and seeing whether there is any mention of the mechanism by which snapshots are deleted. However, the bulk of the work on this bug will be conceptual and centered around the Technical Guide.
oVirt feature page: http://www.ovirt.org/Features/Live_Merge#Special_considerations_for_ovirt-engine
PRD Bug: https://bugzilla.redhat.com/show_bug.cgi?id=647386
The two child bugs for this tracker bug have now been addressed and verified.