Thank you all for your answers.
My problem with Hadoop on Ubuntu is that I cannot make the DataNode
server to work properly (at least this is where I think the error is). I
get an "File jobtracker.info could only be replicated to 0 nodes instead
of 1" error message. All other servers are running fine. I am running
Hadoop in a single (test) machine.
The results for jps and netstats are:
jps
4465 NameNode
4553 DataNode
5105 Jps
4717 JobTracker
4649 SecondaryNameNode
4807 TaskTracker
sudo netstat -plten | grep java
tcp 0 0 0.0.0.0:50722 0.0.0.0:*
LISTEN 1000 13858 4553/java
tcp 0 0 0.0.0.0:50020 0.0.0.0:*
LISTEN 1000 15130 4553/java
tcp 0 0 127.0.0.1:54310 0.0.0.0:*
LISTEN 1000 13564 4465/java
tcp 0 0 127.0.0.1:54311 0.0.0.0:*
LISTEN 1000 14571 4717/java
tcp 0 0 0.0.0.0:59080 0.0.0.0:*
LISTEN 1000 14547 4717/java
tcp 0 0 0.0.0.0:50090 0.0.0.0:*
LISTEN 1000 14943 4649/java
tcp 0 0 127.0.0.1:40555 0.0.0.0:*
LISTEN 1000 15057 4807/java
tcp 0 0 0.0.0.0:50060 0.0.0.0:*
LISTEN 1000 15031 4807/java
tcp 0 0 0.0.0.0:47661 0.0.0.0:*
LISTEN 1000 14247 4649/java
tcp 0 0 0.0.0.0:50030 0.0.0.0:*
LISTEN 1000 14941 4717/java
tcp 0 0 0.0.0.0:57839 0.0.0.0:*
LISTEN 1000 13514 4465/java
tcp 0 0 0.0.0.0:50070 0.0.0.0:*
LISTEN 1000 14533 4465/java
tcp 0 0 0.0.0.0:50010 0.0.0.0:*
LISTEN 1000 14765 4553/java
tcp 0 0 0.0.0.0:50075 0.0.0.0:*
LISTEN 1000 14946 4553/java
