code: boolean confirmFormat(boolean force, boolean interactive) throws IOException {
      List<FormatConfirmable> confirms = Lists.newArrayList();
      for (StorageDirectory sd : storage.dirIterable(null)) {
        confirms.add(sd);
      }   
      confirms.addAll(editLog.getFormatConfirmables());
      return Storage.confirmFormat(confirms, force, interactive);
    }
docs: Check whether the storage directories and non-file journals exist.
  If running in interactive mode, will prompt the user for each
  directory to allow them to format anyway. Otherwise, returns
  false, unless 'force' is specified.
  
  @param interactive prompt the user when a dir exists
  @return true if formatting should proceed
  @throws IOException if some storage cannot be accessed