private void usage(final String errorMsg) {
    if (errorMsg != null && errorMsg.length() > 0) {
      System.err.println("ERROR: " + errorMsg);
    }
    System.err.println("Usage: " + NAME + " [options] <HFile inputdir(s)> <table>");
    System.err.println("Read all HFile's for <table> and split them to <table> region boundaries.");
    System.err.println("<table>  table to load.\n");
    System.err.println("To generate HFiles for a bulk data load, pass the option:");
    System.err.println("  -D" + BULK_OUTPUT_CONF_KEY + "=/path/for/output");
    System.err.println("Other options:");
    System.err.println("   -D " + JOB_NAME_CONF_KEY
      + "=jobName - use the specified mapreduce job name for the HFile splitter");
    System.err.println("For performance also consider the following options:\n"
      + "  -Dmapreduce.map.speculative=false\n" + "  -Dmapreduce.reduce.speculative=false");
  }
Print usage
@param errorMsg Error message. Can be null.
hbase-backup/src/main/java/org/apache/hadoop/hbase/backup/mapreduce/MapReduceHFileSplitterJob.java