5.11. Cloning volumes

⁠5.11. Cloning volumes

Cloning a storage volume is similar to creating a new storage volume, except that an existing storage volume is used for most of the attributes. Only the name and permissions in the XML parameter are used for the new volume, everything else is inherited from the existing volume.

It should be noted that cloning can take a very long time to accomplish, depending on the size of the storage volume being cloned. This is because the clone process copies the data from the source volume to the new target volume.

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Example 5.10. Clone an existing storage volume

# Example-.py
#!/usr/bin/env python3
import sys
import libvirt

stgvol_xml = """
<volume>
  <name>sparse.img</name>
  <allocation>0</allocation>
  <capacity unit="G">2</capacity>
  <target>
    <path>/var/lib/virt/images/sparse.img</path>
    <permissions>
      <owner>107</owner>
      <group>107</group>
      <mode>0744</mode>
      <label>virt_image_t</label>
    </permissions>
  </target>
</volume>"""
stgvol_xml2 = """
<volume>
  <name>sparse2.img</name>
  <allocation>0</allocation>
  <capacity unit="G">2</capacity>
  <target>
    <path>/var/lib/virt/images/sparse.img</path>
    <permissions>
      <owner>107</owner>
      <group>107</group>
      <mode>0744</mode>
      <label>virt_image_t</label>
    </permissions>
  </target>
</volume>"""
pool = 'default'

conn = None
try:
    conn = libvirt.open("qemu:///system")
except libvirt.libvirtError as e:
    print(repr(e), file=sys.stderr)
    exit(1)

pool = conn.storagePoolLookupByName(pool)
if pool == None:
    print('Failed to locate any StoragePool objects.', file=sys.stderr)
    exit(1)

# create a new storage volume
stgvol = pool.createXML(stgvol_xml, 0)
if stgvol == None:
    print('Failed to create a  StorageVol object.', file=sys.stderr)
    exit(1)

# now clone the existing storage volume
print('This could take some time...')
stgvol2 = pool.createXMLFrom(stgvol_xml2, stgvol, 0)
if stgvol2 == None:
    print('Failed to clone a  StorageVol object.', file=sys.stderr)
    exit(1)

# remove the cloned storage volume
# physically remove the storage volume from the underlying disk media
stgvol2.wipe(0)
# logically remove the storage volume from the storage pool
stgvol2.delete(0)

# remove the storage volume
# physically remove the storage volume from the underlying disk media
stgvol.wipe(0)
# logically remove the storage volume from the storage pool
stgvol.delete(0)

conn.close()
exit(0)