Hello,
I was trying incremental backup with the provided /usr/share/doc/python3-ovirt-engine-sdk4/examples/backup_vm.py and began using the "full" option.
But I specified an incorrect dir and during backup I got error due to filesystem full

[ 156.7 ] Creating image transfer for disk '33b0f6fb-a855-465d-a628-5fce9b64496a'
[ 157.8 ] Image transfer 'ccc386d3-9f9d-4727-832a-56d355d60a95' is ready
--- Logging error ---, 105.02 seconds, 147.48 MiB/s                            
Traceback (most recent call last):
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/io.py", line 242, in _run
    handler.copy(req)
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/io.py", line 286, in copy
    self._src.write_to(self._dst, req.length, self._buf)
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/backends/http.py", line 216, in write_to
    writer.write(view[:n])
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/backends/nbd.py", line 118, in write
    self._client.write(self._position, buf)
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/nbd.py", line 445, in write
    self._recv_reply(cmd)
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/nbd.py", line 980, in _recv_reply
    if self._recv_reply_chunk(cmd):
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/nbd.py", line 1031, in _recv_reply_chunk
    self._handle_error_chunk(length, flags)
  File "/usr/lib64/python3.6/site-packages/ovirt_imageio/_internal/nbd.py", line 1144, in _handle_error_chunk
    raise ReplyError(code, message)
ovirt_imageio._internal.nbd.ReplyError: Writing to file failed: [Error 28] No space left on device

Now if I try the same backup command (so with "full" option) and I get

ovirtsdk4.Error: Fault reason is "Operation Failed". Fault detail is "[Cannot backup VM. The VM is during a backup operation.]". HTTP response code is 409.

How can I clean the situation?

BTW: the parameter to put into ovirt.conf is backup-dir or backup_dir or what?

Thanks,
Gianluca