class DataStorage extends Storage {

  void recoverTransitionRead(DataNode datanode, NamespaceInfo nsInfo,
      Collection<StorageLocation> dataDirs, StartupOption startOpt) throws IOException {
    if (addStorageLocations(datanode, nsInfo, dataDirs, startOpt).isEmpty()) {
      throw new IOException("All specified directories are failed to load.");
    }
  }

    DataStorage();
  public  DataStorage(StorageInfo storageInfo);

}