/**
   * If ramDiskStorageLimit is >=0, then RAM_DISK capacity is artificially capped. If
   * ramDiskStorageLimit < 0 then it is ignored.
   */
  protected final void startUpCluster(
      final int numDataNodes,
      final StorageType[] storageTypes,
      final long ramDiskStorageLimit,
      final boolean useSCR)
      throws IOException {

    Configuration conf = new Configuration();
    conf.setLong(DFS_BLOCK_SIZE_KEY, BLOCK_SIZE);
    conf.setInt(
        DFS_NAMENODE_LAZY_PERSIST_FILE_SCRUB_INTERVAL_SEC, LAZY_WRITE_FILE_SCRUBBER_INTERVAL_SEC);
    conf.setLong(DFS_HEARTBEAT_INTERVAL_KEY, HEARTBEAT_INTERVAL_SEC);
    conf.setInt(DFS_NAMENODE_HEARTBEAT_RECHECK_INTERVAL_KEY, HEARTBEAT_RECHECK_INTERVAL_MSEC);
    conf.setInt(DFS_DATANODE_LAZY_WRITER_INTERVAL_SEC, LAZY_WRITER_INTERVAL_SEC);

    if (useSCR) {
      conf.setBoolean(DFS_CLIENT_READ_SHORTCIRCUIT_KEY, useSCR);
      conf.set(DFS_CLIENT_CONTEXT, UUID.randomUUID().toString());
      sockDir = new TemporarySocketDirectory();
      conf.set(
          DFS_DOMAIN_SOCKET_PATH_KEY,
          new File(sockDir.getDir(), this.getClass().getSimpleName() + "._PORT.sock")
              .getAbsolutePath());
      conf.set(
          DFS_BLOCK_LOCAL_PATH_ACCESS_USER_KEY,
          UserGroupInformation.getCurrentUser().getShortUserName());
    }

    cluster =
        new MiniDFSCluster.Builder(conf)
            .numDataNodes(numDataNodes)
            .storageTypes(
                storageTypes != null ? storageTypes : new StorageType[] {DEFAULT, DEFAULT})
            .build();
    fs = cluster.getFileSystem();
    client = fs.getClient();

    // Artificially cap the storage capacity of the RAM_DISK volume.
    if (ramDiskStorageLimit >= 0) {
      List<? extends FsVolumeSpi> volumes =
          cluster.getDataNodes().get(0).getFSDataset().getVolumes();

      for (FsVolumeSpi volume : volumes) {
        if (volume.getStorageType() == RAM_DISK) {
          ((FsVolumeImpl) volume).setCapacityForTesting(ramDiskStorageLimit);
        }
      }
    }

    LOG.info("Cluster startup complete");
  }