code: def sds(self):
          
          self.connection._check_login()
          response = self.connection._do_get("{}/{}".format(self.connection._api_url,"types/Sds/instances")).json()
          all_sds = []
          for sds in response:
              all_sds.append(
                  SIO_SDS.from_dict(sds)
              )
          return all_sds
docs: Returns a `list` of all the `ScaleIO_SDS` known to the cluster.  Updates every time - no caching.
          :return: a `list` of all the `ScaleIO_SDS` known to the cluster.
          :rtype: list