Examples of org.apache.hadoop.hdfs.server.datanode.DataNode

Package org.apache.hadoop.hdfs.server.datanode

Examples of org.apache.hadoop.hdfs.server.datanode.DataNode

org.apache.hadoop.hdfs.server.datanode.DataNode
DataNode is a class (and program) that stores a set of blocks for a DFS deployment. A single deployment can have one or many DataNodes. Each DataNode communicates regularly with a single NameNode. It also communicates with client code and other DataNodes from time to time. DataNodes store a series of named blocks. The DataNode allows client code to read these blocks, or to write new block data. The DataNode may also, in response to instructions from its NameNode, delete blocks or copy blocks to/from other DataNodes. The DataNode maintains just one critical table: block-> stream of bytes (of BLOCK_SIZE or less) This info is stored on a local disk. The DataNode reports the table's contents to the NameNode upon startup and every so often afterwards. DataNodes spend their lives in an endless loop of asking the NameNode for something to do. A NameNode cannot connect to a DataNode directly; a NameNode simply returns values from functions invoked by a DataNode. DataNodes maintain an open server socket so that client code or other DataNodes can read/write data. The host/port for this server is reported to the NameNode, which then sends that information to clients or other DataNodes that might be interested.

    conf.set(DFSConfigKeys.DFS_BLOCK_LOCAL_PATH_ACCESS_USER_KEY,
        "alloweduser1,alloweduser2");
    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).numDataNodes(1)
        .format(true).build();
    cluster.waitActive();
    final DataNode dn = cluster.getDataNodes().get(0);
    FileSystem fs = cluster.getFileSystem();
    try {
      DFSTestUtil.createFile(fs, new Path("/tmp/x"), 16, (short) 1, 23);
      UserGroupInformation aUgi1 =
          UserGroupInformation.createRemoteUser("alloweduser1");

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  /**
   * Check whether the data-node can be started.
   */
  private boolean canStartDataNode(Configuration conf) throws IOException {
    DataNode dn = null;
    try {
      dn = DataNode.createDataNode(new String[]{}, conf);
    } catch(IOException e) {
      if (e instanceof java.net.BindException)
        return false;
      throw e;
    }
    dn.shutdown();
    return true;
  }

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      }
      Configuration newconf = new Configuration(dnConf); // save config
      if (hosts != null) {
        NetUtils.addStaticResolution(hosts[i - curDatanodesNum], "localhost");
      }
      DataNode dn = DataNode.instantiateDataNode(dnArgs, dnConf);
      //since the HDFS does things based on IP:port, we need to add the mapping
      //for IP:port to rackId
      String ipAddr = dn.getSelfAddr().getAddress().getHostAddress();
      if (racks != null) {
        int port = dn.getSelfAddr().getPort();
        System.out.println("Adding node with IP:port : " + ipAddr + ":" + port+
                            " to rack " + racks[i-curDatanodesNum]);
        StaticMapping.addNodeToRack(ipAddr + ":" + port,
                                  racks[i-curDatanodesNum]);
      }

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   * Gets a list of the started DataNodes.  May be empty.
   */
  public ArrayList<DataNode> getDataNodes() {
    ArrayList<DataNode> list = new ArrayList<DataNode>();
    for (int i = 0; i < dataNodes.size(); i++) {
      DataNode node = dataNodes.get(i).datanode;
      list.add(node);
    }
    return list;
  }

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   * is left running so that new DataNodes may be started.
   */
  public void shutdownDataNodes() {
    for (int i = dataNodes.size()-1; i >= 0; i--) {
      System.out.println("Shutting down DataNode " + i);
      DataNode dn = dataNodes.remove(i).datanode;
      dn.shutdown();
      numDataNodes--;
    }
  }

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  public synchronized DataNodeProperties stopDataNode(int i) {
    if (i < 0 || i >= dataNodes.size()) {
      return null;
    }
    DataNodeProperties dnprop = dataNodes.remove(i);
    DataNode dn = dnprop.datanode;
    System.out.println("MiniDFSCluster Stopping DataNode " + 
                       dn.dnRegistration.getName() +
                       " from a total of " + (dataNodes.size() + 1) + 
                       " datanodes.");
    dn.shutdown();
    numDataNodes--;
    return dnprop;
  }

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   * Shutdown a datanode by name.
   */
  public synchronized DataNodeProperties stopDataNode(String name) {
    int i;
    for (i = 0; i < dataNodes.size(); i++) {
      DataNode dn = dataNodes.get(i).datanode;
      if (dn.dnRegistration.getName().equals(name)) {
        break;
      }
    }
    return stopDataNode(i);

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      // Check storage usage 
      // can't check capacities for real storage since the OS file system may be changing under us.
      if (simulatedStorage) {
        DataNode dn = cluster.getDataNodes().get(0);
        assertEquals(fileSize, dn.getFSDataset().getDfsUsed());
        assertEquals(SimulatedFSDataset.DEFAULT_CAPACITY-fileSize, dn.getFSDataset().getRemaining());
      }
    } finally {
      cluster.shutdown();
    }
  }

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          f, 0, Long.MAX_VALUE);
      assertEquals(1, locations.locatedBlockCount());
      LocatedBlock locatedblock = locations.getLocatedBlocks().get(0);
      int successcount = 0;
      for(DatanodeInfo datanodeinfo: locatedblock.getLocations()) {
        DataNode datanode = cluster.getDataNode(datanodeinfo.ipcPort);
        FSDataset dataset = (FSDataset)datanode.data;
        Block b = dataset.getStoredBlock(locatedblock.getBlock().getBlockId());
        File blockfile = dataset.findBlockFile(b.getBlockId());
        System.out.println("blockfile=" + blockfile);
        if (blockfile != null) {

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      // Check storage usage 
      // can't check capacities for real storage since the OS file system may be changing under us.
      if (simulatedStorage) {
        DataNode dn = cluster.getDataNodes().get(0);
        assertEquals(fileSize, dn.getFSDataset().getDfsUsed());
        assertEquals(SimulatedFSDataset.DEFAULT_CAPACITY-fileSize, dn.getFSDataset().getRemaining());
      }
    } finally {
      cluster.shutdown();
    }
  }

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