code: @SuppressWarnings("unused")
  	private void genFile(Path file, long fileSize) throws IOException {
  		FSDataOutputStream out = fs.create(file, true,
  				getConf().getInt("io.file.buffer.size", 4096),
  				(short) getConf().getInt("dfs.replication", 3),
  				fs.getDefaultBlockSize());
  		for (long i = 0; i < fileSize; i++) {
  			out.writeByte('a');
  		}
  		out.close();
  	}
docs: Create a file with the name <code>file</code> and a length of
  <code>fileSize</code>. The file is filled with character 'a'.