Why won't it boot from snapshot?

Question

Backup

Problem: Can't boot from snapshot (hangs when desktop starts loading)
Suspicions:

Format specific information:
    compat: 1.1
    lazy refcounts: false

More:
I want to make a backup using copies of snapshots. To do this, I used this advice

[email protected]:/var/lib/libvirt/images# qemu-img create -f qcow2 -b win81.img win81.qcow2.snap
Formatting 'win81.qcow2.snap', fmt=qcow2 size=214748364800 backing_file='win81.img' encryption=off cluster_size=65536 lazy_refcounts=off 
[email protected]:/var/lib/libvirt/images# ls -l
-rw------- 1 root root 214748364800 дек.  21 11:27 win81.img
-rw-r--r-- 1 root root       200192 дек.  21 11:27 win81.qcow2.snap

[email protected]:/var/lib/libvirt/images# sudo virsh shutdown win81
Завершение работы домена win81

Next, we go to change the xml file.
[email protected]:nano /etc/libvirt/qemu/win81.xml

<domain type='kvm'>
  <name>win81</name>
  <uuid>083283e5-ce0b-0905-b491-3fe01cf042ea</uuid>
  <memory unit='KiB'>2097152</memory>
  <currentMemory unit='KiB'>2097152</currentMemory>
  <vcpu placement='static'>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-trusty'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='localtime'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/kvm-spice</emulator>

БЫЛО
    <disk type='file' device='disk'>
--      <driver name='qemu' type=‘qcow2’/>
--      <source file='/var/lib/libvirt/images/win81.qcow2.snap/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>

СТАЛО
    <disk type='file' device='disk'>
++      <driver name='qemu' type='raw'/>
++      <source file='/var/lib/libvirt/images/win81.img'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>

[email protected]:/var/lib/libvirt/images# ls -l
-rw------- 1 root root 214748364800 дек.  21 11:27 win81.img
-rw-r--r-- 1 root root       200192 дек.  21 11:27 win81.qcow2.snap
[email protected]:/var/lib/libvirt/images# virsh start win81
Домен win81 запущен

I look through vnc and see how to boot Windows. Upon completion of loading the Windows icon, a mouse appears on a black screen and nothing else loads (waited 10 minutes)
I look here.

[email protected]:/var/lib/libvirt/images# qemu-img info win81.qcow2.snap 
image: win81.qcow2.snap
file format: qcow2
virtual size: 200G (214748364800 bytes)
disk size: 196K
cluster_size: 65536
backing file: win81.img
Format specific information:
    compat: 1.1
    lazy refcounts: false

Since I don’t really understand all this cuisine, I was alerted by lazy refcounts: false. In the search they write that this is some kind of bug that is being fixed . But is it the case - he did not pick.

[email protected]:/etc/libvirt/qemu# virsh version
Собрано при помощи библиотеки: libvirt 1.2.2
Используется библиотека: libvirt 1.2.2
Используется API: QEMU 1.2.2
Выполняется гипервизор: QEMU 2.0.0

Maybe he made a mistake in the actions due to inexperience?