'Manage an existing lun in the array.
The lun should be in a manageable pool backend, otherwise
error would return.
Rename the backend storage object so that it matches the,
volume[\'name\'] which is how drivers traditionally map between a
cinder volume and the associated backend storage object.
.. code-block:: default
existing_ref:{
\'id\':lun_id'

def manage_existing(self, volume, existing_ref):

    LOG.debug('manage_existing    volume    id=%(volume_id)s    existing_ref    source    id=%(source_id)s', {'volume_id': volume['id'], 'source_id': existing_ref['source-id']})
    return self.common.manage_existing(volume, existing_ref)
