On EL 6.5 Host and oVirt 3.5, I was able to create live snapshot (Live
Snapshot Support: Active).
After upgrading host to EL 6.6, the oVirt UI now reports live snapshot as
"Inactive".
I have submitted bug 1158469 with more details (package versions, etc).
https://bugzilla.redhat.com/show_bug.cgi?id=1158469
I would assume that is it not advisable to upgrade from EL 6.5 to EL 6.6 at
this time if you require Live Snapshot support on the Host.