'Backup volume metadata.
NOTE(dosaboy): the metadata we are backing up is obtained from a
versioned api so we should not alter it in any way here.
We must also be sure that the service that will perform
the restore is compatible with version used.'

def _backup_metadata(self, backup, object_meta):

    json_meta = self.get_metadata(backup['volume_id'])
    if (not json_meta):
        LOG.debug('No    volume    metadata    to    backup.')
        return
    object_meta['volume_meta'] = json_meta
