内部スナップショットは、10 qcow2バクアップ 内部スナップショット(internal)

root@hvdev1001:~# virsh domblklist testvm
 Target   Source
------------------------------------------------
 vda      /var/lib/libvirt/images/testvm.qcow2
 sda      -

root@hvdev1001:~# virsh snapshot-create-as testvm --name testsnap --no-metadata --disk-only 
Domain snapshot testsnap created

root@hvdev1001:~# virsh domblklist testvm
 Target   Source
---------------------------------------------------
 vda      /var/lib/libvirt/images/testvm.testsnap
 sda      -

# virsh dumpxml testvm
.
.
.
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/testvm.testsnap' index='3'/>
      <backingStore type='file' index='2'>
        <format type='qcow2'/>
        <source file='/var/lib/libvirt/images/testvm.qcow2'/>
        <backingStore/>
      </backingStore>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
    </disk>
.
.

# qemu-img info /var/lib/libvirt/images/testvm.qcow2 
image: /var/lib/libvirt/images/testvm.qcow2
file format: qcow2
virtual size: 25 GiB (26843545600 bytes)
disk size: 4.16 GiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: true
    refcount bits: 16
    corrupt: false

# cp /var/lib/libvirt/images/testvm.qcow2 /backups/

容量の節約には圧縮しとく方法もある。
※コンバートには時間がかかります。

# qemu-img convert -c -f qcow2 -O qcow2 /var/lib/libvirt/images/testvm.qcow2 /backups/testvm.qcow2.bk

# qemu-img info /var/lib/libvirt/images/testvm.qcow2
image: testvm.qcow2
file format: qcow2
virtual size: 100 GiB (107374182400 bytes)
disk size: 12.9 GiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: true
    refcount bits: 16
    corrupt: false
# qemu-img info /backups/testvm.qcow2.bk
image: testvm.qcow2.bk
file format: qcow2
virtual size: 100 GiB (107374182400 bytes)
disk size: 6.88 GiB
cluster_size: 65536
Format specific information:
    compat: 1.1
    lazy refcounts: false
    refcount bits: 16
    corrupt: false
# ll -h /backups/testvm.qcow2.bk
-rw-r--r-- 1 root         root 6.9G Apr 28 07:55 /backups/testvm.qcow2.bk

※注意 –base –topはフルパスじゃないとエラーになります。

root@hvdev1001:~# virsh blockcommit testvm vda --base /var/lib/libvirt/images/testvm.qcow2 --top /var/lib/libvirt/images/testvm.testsnap --wait --verbose --pivot 
Block commit: [100 %]
Successfully pivoted

root@hvdev1001:~# virsh domblklist testvm 
 Target   Source
------------------------------------------------
 vda      /var/lib/libvirt/images/testvm.qcow2
 sda      -

# virsh dumpxml testvm
.
.
.
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/testvm.qcow2' index='2'/>
      <backingStore/>
      <target dev='vda' bus='virtio'/>
      <alias name='virtio-disk0'/>
      <address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
    </disk>