[CentOS-devel] centos6.3 qemu-kvm question

hello hackers:
  i am using qemu-kvm with libvirt on centos6.3,i found that the
qemu-kvm does not support disk only snapshot,
when i use virsh snapshot-create-as --disk-only ,it will raise an
error :the qemu-kvm binary does not support blkdev_snapshot
but the qemu-kvm-rhev  which come from RHEV works .

is there any one know why the qemu-kvm-el6 does not support disk only
snapshot feature?
 thanks.