hadoop/conf/hadoop-default.xml

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>

<!-- Do not modify this file directly.  Instead, copy entries that you -->
<!-- wish to modify from this file into hadoop-site.xml and change them -->
<!-- there.  If hadoop-site.xml does not already exist, create it.      -->

<configuration>

<!-- i/o properties -->

<property>
  <name>io.sort.factor</name>
  <value>10</value>
  <description>The number of streams to merge at once while sorting
  files.  This determines the number of open file handles.</description>
</property>

<property>
  <name>io.sort.mb</name>
  <value>100</value>
  <description>The total amount of buffer memory to use while sorting 
  files, in megabytes.  By default, gives each merge stream 1MB, which
  should minimize seeks.</description>
</property>

<property>
  <name>io.file.buffer.size</name>
  <value>4096</value>
  <description>The size of buffer for use in sequence files.
  The size of this buffer should probably be a multiple of hardware
  page size (4096 on Intel x86), and it determines how much data is
  buffered during read and write operations.</description>
</property>
  
<property>
  <name>io.bytes.per.checksum</name>
  <value>512</value>
  <description>The number of bytes per checksum.  Must not be larger than
  io.file.buffer.size.</description>
</property>

<property>
  <name>io.skip.checksum.errors</name>
  <value>false</value>
  <description>If true, when a checksum error is encountered while
  reading a sequence file, entries are skipped, instead of throwing an
  exception.</description>
</property>
  
<property>
  <name>io.map.index.skip</name>
  <value>0</value>
  <description>Number of index entries to skip between each entry.
  Zero by default. Setting this to values larger than zero can
  facilitate opening large map files using less memory.</description>
</property>

<!-- file system properties -->

<property>
  <name>fs.default.name</name>
  <value>local</value>
  <description>The name of the default file system.  Either the
  literal string "local" or a host:port for DFS.</description>
</property>

<property>
  <name>dfs.datanode.port</name>
  <value>50010</value>
  <description>The port number that the dfs datanode server uses as a starting 
	       point to look for a free port to listen on.
</description>
</property>

<property>
  <name>dfs.name.dir</name>
  <value>/tmp/hadoop/dfs/name</value>
  <description>Determines where on the local filesystem the DFS name node
      should store the name table.</description>
</property>

<property>
  <name>dfs.data.dir</name>
  <value>/tmp/hadoop/dfs/data</value>
  <description>Determines where on the local filesystem an DFS data node
  should store its blocks.  If this is a comma- or space-delimited
  list of directories, then data will be stored in all named
  directories, typically on different devices.</description>
</property>

<property>
  <name>dfs.replication</name>
  <value>3</value>
  <description>How many copies we try to have at all times. The actual
  number of replications is at max the number of datanodes in the
  cluster.</description>
</property>

<property>
  <name>dfs.df.interval</name>
  <value>3000</value>
  <description>Disk usage statistics refresh interval in msec.</description>
</property>

<!-- map/reduce properties -->

<property>
  <name>mapred.job.tracker</name>
  <value>local</value>
  <description>The host and port that the MapReduce job tracker runs
  at.  If "local", then jobs are run in-process as a single map
  and reduce task.
  </description>
</property>

<property>
  <name>mapred.job.tracker.info.port</name>
  <value>50030</value>
  <description>The port that the MapReduce job tracker info webserver runs at.
  </description>
</property>

<property>
  <name>mapred.task.tracker.output.port</name>
  <value>50040</value>
  <description>The port number that the MapReduce task tracker output server uses as a starting
               point to look for a free port to listen on.
  </description>
</property>

<property>
  <name>mapred.task.tracker.report.port</name>
  <value>50050</value>
  <description>The port number that the MapReduce task tracker report server uses as a starting
               point to look for a free port to listen on.
  </description>
</property>

<property>
  <name>mapred.local.dir</name>
  <value>/tmp/hadoop/mapred/local</value>
  <description>The local directory where MapReduce stores intermediate
  data files.  May be a space- or comma- separated list of
  directories on different devices in order to spread disk i/o.
  </description>
</property>

<property>
  <name>mapred.system.dir</name>
  <value>/tmp/hadoop/mapred/system</value>
  <description>The shared directory where MapReduce stores control files.
  </description>
</property>

<property>
  <name>mapred.temp.dir</name>
  <value>/tmp/hadoop/mapred/temp</value>
  <description>A shared directory for temporary files.
  </description>
</property>

<property>
  <name>mapred.map.tasks</name>
  <value>2</value>
  <description>The default number of map tasks per job.  Typically set
  to a prime several times greater than number of available hosts.
  Ignored when mapred.job.tracker is "local".  
  </description>
</property>

<property>
  <name>mapred.reduce.tasks</name>
  <value>1</value>
  <description>The default number of reduce tasks per job.  Typically set
  to a prime close to the number of available hosts.  Ignored when
  mapred.job.tracker is "local".
  </description>
</property>

<property>
  <name>mapred.task.timeout</name>
  <value>600000</value>
  <description>The number of milliseconds before a task will be
  terminated if it neither reads an input, writes an output, nor
  updates its status string.
  </description>
</property>

<property>
  <name>mapred.tasktracker.tasks.maximum</name>
  <value>2</value>
  <description>The maximum number of tasks that will be run
  simultaneously by a task tracker.
  </description>
</property>

<property>
  <name>mapred.child.java.opts</name>
  <value>-Xmx200m</value>
  <description>Java opts for the task tracker child processes.  Subsumes
  'mapred.child.heap.size' (If a mapred.child.heap.size value is found
  in a configuration, its maximum heap size will be used and a warning
  emitted that heap.size has been deprecated). Also, the following symbols,
  if present, will be interpolated: @taskid@ is replaced by current TaskID;
  and @port@ will be replaced by mapred.task.tracker.report.port + 1 (A second
  child will fail with a port-in-use if mapred.tasktracker.tasks.maximum is
  greater than one). Any other occurrences of '@' will go unchanged. For
  example, to enable verbose gc logging to a file named for the taskid in
  /tmp and to set the heap maximum to be a gigabyte, pass a 'value' of:

        -Xmx1024m -verbose:gc -Xloggc:/tmp/@taskid@.gc
  </description>
</property>

<property>
  <name>mapred.combine.buffer.size</name>
  <value>100000</value>
  <description>The number of entries the combining collector caches before
  combining them and writing to disk.</description>
</property>

<property>
  <name>mapred.speculative.execution</name>
  <value>true</value>
  <description>If true, then multiple instances of some map tasks may
  be executed in parallel.</description>
</property>

<property>
  <name>mapred.min.split.size</name>
  <value>0</value>
  <description>The minimum size chunk that map input should be split
  into.  Note that some file formats may have minimum split sizes that
  take priority over this setting.</description>
</property>


<!-- ipc properties -->

<property>
  <name>ipc.client.timeout</name>
  <value>60000</value>
  <description>Defines the timeout for IPC calls in milliseconds.</description>
</property>

</configuration>