NameNode nn = null;
String blockPoolId = null;
private void startCluster() throws IOException {
conf = new HdfsConfiguration();
cluster = new Builder(conf).numDataNodes(REPL_FACTOR).build();
cluster.waitActive();
fs = cluster.getFileSystem();
nn = cluster.getNameNode(0);
assertNotNull(nn);
dn = cluster.getDataNodes().get(0);