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MapReduce, mail # user - Is it necessary to run secondary namenode when starting HDFS?


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Is it necessary to run secondary namenode when starting HDFS?
Ivan Ryndin 2012-12-17, 17:04
Hi all,

is it necessary to run secondary namenode when starting HDFS?
I am dealing with Hadoop 1.1.1.
Looking at script $HADOOP_HOME/bin/start_dfs.sh
There are next lines in this file:

# start dfs daemons
# start namenode after datanodes, to minimize time namenode is up w/o data
# note: datanodes will log connection errors until namenode starts
"$bin"/hadoop-daemon.sh --config $HADOOP_CONF_DIR start namenode
$nameStartOpt
"$bin"/hadoop-daemons.sh --config $HADOOP_CONF_DIR start datanode
$dataStartOpt
"$bin"/hadoop-daemons.sh --config $HADOOP_CONF_DIR --hosts masters start
secondarynamenode

 So, will HDFS work if I turn off starting of secondarynamenode ?

I do ask this because I am playing with Hadoop on two-node cluster only
(and machines in cluster do not have much RAM and disk space), and thus
don't want to run unnecessary processes.

--
Best regards,
Ivan P. Ryndin,