cloudera 0.18 -> 0.20

 * hadoop install 
{{{
$ sudo su -
# apt-get install hadoop-0.18 hadoop-0.18-namenode  hadoop-conf-pseudo
# apt-get install hadoop-0.18-datanode hadoop-0.18-jobtracker hadoop-0.18-tasktracker
}}}

 * hadoop namenode format
{{{
# su -s /bin/bash - hadoop -c 'hadoop namenode -format'
}}}
   * use instruction 
{{{
# su -s /bin/bash - hadoop -c " COMMAND "
}}}

 * startup 
{{{
# /etc/init.d/hadoop-namenode start
}}}



 * setup the conf files
...
 (hadoop-env.sh, core-site.xml, hdfs-site.xml, mapred-site.xml)
....

 * upgrade cloudera-hadoop-0.18 ---> official-hadoop 0.20
{{{
# su -s /bin/bash - hadoop -c " /opt/hadoop/bin/hadoop namenode -upgrade "
}}}

 * the successful screen shot :
-----------
 [[Image(2010-01-06-181048_959x723_scrot.png)]]
-----------
 * but terminal console is handle by hadoop process 
-----------
 [[Image(2010-01-06-181350_881x389_scrot.png)]]

 * Right now,  our NameNode is in SAFE mode waiting for the DataNodes to connect.

 * Start the rest of HDFS

When the datanodes start, they will connect to the Name Node and an upgrade will be initiated.

{{{
# su -s /bin/bash - hadoop -c "/opt/hadoop/bin/hadoop-daemon.sh start datanode"
}}}

switch to original handled by hadoop namenode console, there will be appear something upgrade information ..
{{{
#!sh

10/01/06 18:08:09 INFO ipc.Server: IPC Server handler 9 on 8020: starting
10/01/07 17:52:26 INFO hdfs.StateChange: BLOCK* NameSystem.registerDatanode: node registration from 127.0.0.1:50010 storage DS-1591516806-127.0.1.1-50010-1262769597737
10/01/07 17:52:26 INFO net.NetworkTopology: Adding a new node: /default-rack/127.0.0.1:50010
10/01/07 17:52:27 INFO hdfs.StateChange: STATE* Safe mode ON. 
The ratio of reported blocks 0.1000 has not reached the threshold 0.9990. Safe mode will be turned off automatically.
10/01/07 17:52:27 INFO hdfs.StateChange: STATE* Safe mode extension entered. 
The ratio of reported blocks 1.0000 has reached the threshold 0.9990. Safe mode will be turned off automatically in 29 seconds.
10/01/07 17:52:47 INFO hdfs.StateChange: STATE* Safe mode ON. 
The ratio of reported blocks 1.0000 has reached the threshold 0.9990. Safe mode will be turned off automatically in 9 seconds.
10/01/07 17:52:57 INFO namenode.FSNamesystem: Total number of blocks = 10
10/01/07 17:52:57 INFO namenode.FSNamesystem: Number of invalid blocks = 0
10/01/07 17:52:57 INFO namenode.FSNamesystem: Number of under-replicated blocks = 0
10/01/07 17:52:57 INFO namenode.FSNamesystem: Number of  over-replicated blocks = 0
10/01/07 17:52:57 INFO hdfs.StateChange: STATE* Leaving safe mode after 85493 secs.
10/01/07 17:52:57 INFO hdfs.StateChange: STATE* Safe mode is OFF.
10/01/07 17:52:57 INFO hdfs.StateChange: STATE* Network topology has 1 racks and 1 datanodes
10/01/07 17:52:57 INFO hdfs.StateChange: STATE* UnderReplicatedBlocks has 0 blocks
}}}

Once all the DataNodes have upgraded, you should see a message that Safe mode will be turned off automatically in X seconds.



 * start MapReduce
After you have verified correct operation of HDFS, you are ready to start MapReduce.

 * finalize the hdfs upgrade

Now that you've confirmed your cluster is successfully running on Hadoop 0.20, you can go ahead and finalize the HDFS upgrade:
{{{{
$ sudo -u hadoop hadoop dfsadmin -finalizeUpgrade
}}}