code: void format(File dnCurDir, NamespaceInfo nsInfo) throws IOException {
      File curNsDir = getNsRoot(namespaceID, dnCurDir);
      StorageDirectory nsSdir = new StorageDirectory(curNsDir);
      format(nsSdir, nsInfo);
    }
docs: Format a namespace slice storage.
  @param dnCurDir DataStorage current directory
  @param nsInfo the name space info
  @throws IOException Signals that an I/O exception has occurred.