private static String createDirAndSetProperty(final String relPath, String property) {
    String path = UTIL.getDataTestDir(relPath).toString();
    System.setProperty(property, path);
    UTIL.getConfiguration().set(property, path);
    new File(path).mkdirs();
    LOG.info("Setting " + property + " to " + path + " in system properties and HBase conf");
    return path;
  }
Creates a directory for the cluster, under the test data
hbase-asyncfs/src/test/java/org/apache/hadoop/hbase/io/asyncfs/AsyncFSTestBase.java