@Override
  protected void printUsage() {
    super.printUsage();
    System.out.println("\n" + "Examples:\n" + "  hbase snapshot export \\\n"
      + "    --snapshot MySnapshot --copy-to hdfs://srv2:8082/hbase \\\n"
      + "    --chuser MyUser --chgroup MyGroup --chmod 700 --mappers 16\n" + "\n"
      + "  hbase snapshot export \\\n"
      + "    --snapshot MySnapshot --copy-from hdfs://srv2:8082/hbase \\\n"
      + "    --copy-to hdfs://srv1:50070/hbase");
  }
Execute the export snapshot by copying the snapshot metadata, hfiles and wals.
@return 0 on success, and != 0 upon failure.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java