[root@ns3354400 ~]# xe pbd-unplug uuid=55ea1c64-df4c-f202-8d71-2bde5a9cc708
There was an SR backend failure.
status: non-zero exit
stdout:
stderr: Traceback (most recent call last):
  File "/opt/xensource/sm/LVMSR", line 2002, in ?
    SRCommand.run(LVHDSR, DRIVER_INFO)
  File "/opt/xensource/sm/SRCommand.py", line 327, in run
    ret = cmd.run(sr)
  File "/opt/xensource/sm/SRCommand.py", line 106, in run
    return self._run_locked(sr)
  File "/opt/xensource/sm/SRCommand.py", line 153, in _run_locked
    return self._run(sr, target)
  File "/opt/xensource/sm/SRCommand.py", line 307, in _run
    return sr.detach(self.params['sr_uuid'])
  File "/opt/xensource/sm/LVMSR", line 584, in detach
    raise Exception("SR detach failed, please refer to the log " \
Exception: SR detach failed, please refer to the log for details.