Hadoop - java.net.ConnectException: Connection refused

Question

I want connect to hdfs (in localhost) and i have a error:

Call From despubuntu-ThinkPad-E420/127.0.1.1 to localhost:54310 failed on connection exception: java.net.Connec

Answer 1

I guess that you didn't set up your hadoop cluster correctly please follow these steps :

Step1: begin with setting up .bashrc:

vi $HOME/.bashrc

put the following lines at the end of the file: (change the hadoop home as yours)

# Set Hadoop-related environment variables
export HADOOP_HOME=/usr/local/hadoop

# Set JAVA_HOME (we will also configure JAVA_HOME directly for Hadoop later on)
export JAVA_HOME=/usr/lib/jvm/java-6-sun

# Some convenient aliases and functions for running Hadoop-related commands
unalias fs &> /dev/null
alias fs="hadoop fs"
unalias hls &> /dev/null
alias hls="fs -ls"

# If you have LZO compression enabled in your Hadoop cluster and
# compress job outputs with LZOP (not covered in this tutorial):
# Conveniently inspect an LZOP compressed file from the command
# line; run via:
#
# $ lzohead /hdfs/path/to/lzop/compressed/file.lzo
#
# Requires installed 'lzop' command.
#
lzohead () {
    hadoop fs -cat $1 | lzop -dc | head -1000 | less
}

# Add Hadoop bin/ directory to PATH
export PATH=$PATH:$HADOOP_HOME/bin

step 2 : edit hadoop-env.sh as following:

# The java implementation to use.  Required.
export JAVA_HOME=/usr/lib/jvm/java-6-sun

step 3 : Now create a directory and set the required ownerships and permissions

$ sudo mkdir -p /app/hadoop/tmp
$ sudo chown hduser:hadoop /app/hadoop/tmp
# ...and if you want to tighten up security, chmod from 755 to 750...
$ sudo chmod 750 /app/hadoop/tmp

step 4 : edit core-site.xml

  hadoop.tmp.dir
  /app/hadoop/tmp



  fs.default.name
  hdfs://localhost:54310

step 5 : edit mapred-site.xml

  mapred.job.tracker
  localhost:54311

step 6 : edit hdfs-site.xml

  dfs.replication
  1

finally format your hdfs (You need to do this the first time you set up a Hadoop cluster)

 $ /usr/local/hadoop/bin/hadoop namenode -format

hope this will help you