Examples of org.apache.hadoop.dfs.NameNode

org.apache.hadoop.dfs.NameNode
NameNode serves as both directory namespace manager and "inode table" for the Hadoop DFS. There is a single NameNode running in any DFS deployment. (Well, except when there is a second backup/failover NameNode.) The NameNode controls two critical tables: 1) filename->blocksequence (namespace) 2) block->machinelist ("inodes") The first table is stored on disk and is very precious. The second table is rebuilt every time the NameNode comes up. 'NameNode' refers to both this class as well as the 'NameNode server'. The 'FSNamesystem' class actually performs most of the filesystem management. The majority of the 'NameNode' class itself is concerned with exposing the IPC interface to the outside world, plus some configuration management. NameNode implements the ClientProtocol interface, which allows clients to ask for DFS services. ClientProtocol is not designed for direct use by authors of DFS client code. End-users should instead use the org.apache.nutch.hadoop.fs.FileSystem class. NameNode also implements the DatanodeProtocol interface, used by DataNode programs that actually store DFS data blocks. These methods are invoked repeatedly and automatically by all the DataNodes in a DFS deployment. @author Mike Cafarella

    String nameFSDir = baseDirSpecified + "/name";
    conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode("localhost", nameNodePort, conf);


    //
    //        start DataNodes
    //
    for (int i = 0; i < dataNodeNum; i++) {

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    String nameFSDir = baseDirSpecified + "/name";
  conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode(new File(nameFSDir), nameNodePort, conf);


     //
      //        start DataNodes
      //
      for (int i = 0; i < dataNodeNum; i++) {

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    String nameFSDir = baseDirSpecified + "/name";
    conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode("localhost", nameNodePort, conf);


    //
    //        start DataNodes
    //
    for (int i = 0; i < dataNodeNum; i++) {

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      cluster = new MiniDFSCluster(conf, 0, false, null);
      cluster.waitActive();
      
      LOG.info("Restarted cluster with just the NameNode");
      
      NameNode namenode = cluster.getNameNode();
      
      assertTrue("No datanode is started. Should be in SafeMode", 
                 namenode.isInSafeMode());
      
      // manually set safemode.
      namenode.setSafeMode(SafeModeAction.SAFEMODE_ENTER);
      
      // now bring up the datanode and wait for it to be active.
      cluster.startDataNodes(conf, 1, true, null, null);
      cluster.waitActive();
      
      LOG.info("Datanode is started.");
      
      try {
        Thread.sleep(2000);
      } catch (InterruptedException ignored) {}
      
      assertTrue("should still be in SafeMode", namenode.isInSafeMode());
      
      namenode.setSafeMode(SafeModeAction.SAFEMODE_LEAVE);
      assertFalse("should not be in SafeMode", namenode.isInSafeMode());
    } finally {
      if(fs != null) fs.close();
      if(cluster!= null) cluster.shutdown();
    }
  }

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    String nameFSDir = baseDirSpecified + "/name";
  conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode(new File[] { new File(nameFSDir) },
        "localhost", nameNodePort, conf);


     //
      //        start DataNodes
      //

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    String nameFSDir = baseDirSpecified + "/name";
    conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode("localhost", nameNodePort, conf);


    //
    //        start DataNodes
    //
    for (int i = 0; i < dataNodeNum; i++) {

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    String nameFSDir = baseDirSpecified + "/name";
  conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode(new File(nameFSDir), "localhost", nameNodePort, conf);


     //
      //        start DataNodes
      //
      for (int i = 0; i < dataNodeNum; i++) {

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    String nameFSDir = baseDirSpecified + "/name";
  conf.set("dfs.name.dir", nameFSDir);
  
    NameNode.format(conf);
    
    nameNodeDaemon = new NameNode(new File(nameFSDir), nameNodePort, conf);


     //
      //        start DataNodes
      //
      for (int i = 0; i < dataNodeNum; i++) {

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  /**
   * Verify JobTracker port usage.
   */
  public void testJobTrackerPorts() throws Exception {
    NameNode nn = null;
    try {
      nn = hdfs.startNameNode();


      // start job tracker on the same port as name-node
      JobConf conf2 = new JobConf(hdfs.getConfig());

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  /**
   * Verify JobTracker port usage.
   */
  public void testTaskTrackerPorts() throws Exception {
    NameNode nn = null;
    JobTracker jt = null;
    try {
      nn = hdfs.startNameNode();


      JobConf conf2 = new JobConf(hdfs.getConfig());

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org.apache.hadoop.dfs.TestSafeMode

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