'Returns the number of volumes attached to specified Dell server.
:param scserver: The Dell backend server object.
:returns: Mapping count.  -1 if there was an error.'

def get_volume_count(self, scserver):

    r = self.client.get(('StorageCenter/ScServer/%s/MappingList' % self._get_id(scserver)))
    if self._check_result(r):
        mappings = self._get_json(r)
        return len(mappings)
    return (-1)
