def create_snapshot(disk_path, snapshot_name):
   """Create a snapshot in a disk image

   :param disk_path: Path to disk image
   :param snapshot_name: Name of snapshot in disk image
   """
   qemu_img_cmd = ('qemu-img', 'snapshot', '-c', snapshot_name, disk_path)
   # NOTE(vish): libvirt changes ownership of images
   execute(*qemu_img_cmd, run_as_root=True)


def delete_snapshot(disk_path, snapshot_name):
   """Create a snapshot in a disk image

   :param disk_path: Path to disk image
   :param snapshot_name: Name of snapshot in disk image
   """
   qemu_img_cmd = ('qemu-img', 'snapshot', '-d', snapshot_name, disk_path)
   # NOTE(vish): libvirt changes ownership of images
   execute(*qemu_img_cmd, run_as_root=True)

def extract_snapshot(disk_path, source_fmt, snapshot_name, out_path, dest_fmt):
   """Extract a named snapshot from a disk image

   :param disk_path: Path to disk image
   :param snapshot_name: Name of snapshot in disk image
   :param out_path: Desired path of extracted snapshot
   """
   # NOTE(markmc): ISO is just raw to qemu-img
   if dest_fmt == 'iso':
       dest_fmt = 'raw'

   qemu_img_cmd = ('qemu-img', 'convert', '-f', source_fmt, '-O', dest_fmt)

   # Conditionally enable compression of snapshots.
   if CONF.libvirt_snapshot_compression and dest_fmt == "qcow2":
       qemu_img_cmd += ('-c',)

   # When snapshot name is omitted we do a basic convert, which
   # is used by live snapshots.
   if snapshot_name is not None:
       qemu_img_cmd += ('-s', snapshot_name)

   qemu_img_cmd += (disk_path, out_path)
   execute(*qemu_img_cmd)

waring: execute  

             subprocess.Popen('',shell=True)

本文转自 swq499809608 51CTO博客，原文链接:http://blog.51cto.com/swq499809608/1214702