hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestSafeMode.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hdfs.server.namenode;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.HdfsConfiguration;
import org.apache.hadoop.hdfs.MiniDFSCluster;

import org.junit.Test;
import static org.junit.Assert.*;

/**
 * Tests to verify safe mode correctness.
 */
public class TestSafeMode {
  
  /**
   * Verify that the NameNode stays in safemode when dfs.safemode.datanode.min
   * is set to a number greater than the number of live datanodes.
   */
  @Test
  public void testDatanodeThreshold() throws IOException {
    MiniDFSCluster cluster = null;
    DistributedFileSystem fs = null;
    try {
      Configuration conf = new HdfsConfiguration();
      conf.setInt(DFSConfigKeys.DFS_NAMENODE_SAFEMODE_EXTENSION_KEY, 0);
      conf.setInt(DFSConfigKeys.DFS_NAMENODE_SAFEMODE_MIN_DATANODES_KEY, 1);

      // bring up a cluster with no datanodes
      cluster = new MiniDFSCluster.Builder(conf).numDataNodes(0).format(true).build();
      cluster.waitActive();
      fs = (DistributedFileSystem)cluster.getFileSystem();

      assertTrue("No datanode started, but we require one - safemode expected",
                 fs.setSafeMode(SafeModeAction.SAFEMODE_GET));

      String tipMsg = cluster.getNamesystem().getSafeModeTip();
      assertTrue("Safemode tip message looks right",
                 tipMsg.contains("The number of live datanodes 0 needs an additional " +
                                 "2 live datanodes to reach the minimum number 1. " +
                                 "Safe mode will be turned off automatically."));

      // Start a datanode
      cluster.startDataNodes(conf, 1, true, null, null);

      // Wait long enough for safemode check to refire
      try {
        Thread.sleep(1000);
      } catch (InterruptedException ignored) {}

      // We now should be out of safe mode.
      assertFalse(
        "Out of safe mode after starting datanode.",
        fs.setSafeMode(SafeModeAction.SAFEMODE_GET));
    } finally {
      if (fs != null) fs.close();
      if (cluster != null) cluster.shutdown();
    }
  }
}