@Before
  public void setUp() throws Exception {
    htu = new HBaseTestingUtil();
    htu.getConfiguration().setInt("dfs.blocksize", 1024);// For the test with multiple blocks
    htu.getConfiguration().setInt("dfs.replication", 3);
    htu.startMiniDFSCluster(3, new String[] { "/r1", "/r2", "/r3" },
      new String[] { host1, host2, host3 });

    conf = htu.getConfiguration();
    cluster = htu.getDFSCluster();
    dfs = (DistributedFileSystem) FileSystem.get(conf);
  }
Tests for the hdfs fix from HBASE-6435. Please don't add new subtest which involves starting /
stopping MiniDFSCluster in this class. When stopping MiniDFSCluster, shutdown hooks would be
cleared in hadoop's ShutdownHookManager in hadoop 3. This leads to 'Failed suppression of fs
shutdown hook' error in region server.
hbase-server/src/test/java/org/apache/hadoop/hbase/fs/TestBlockReorderMultiBlocks.java