private String getPreserveString(HiveConf clonedConf) {
    List<String> distCpOptions = constructDistCpOptions(clonedConf);
    for (String option : distCpOptions) {
      if (option.startsWith("-p")) {

        return option.replaceFirst("-p", "");
      }
    }
    return "";
  }
DirCopyTask, mainly to be used to copy External table data.
ql/src/java/org/apache/hadoop/hive/ql/exec/repl/DirCopyTask.java