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


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Re: Is it necessary to run secondary namenode when starting HDFS?
Patai Sangbutsarakum 2012-12-17, 18:52
> is it necessary to run secondary namenode when starting HDFS?
I would say it's not necessary. I did skip it when I first played with Hadoop.

From: Ivan Ryndin <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Reply-To: <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Date: Mon, 17 Dec 2012 21:04:49 +0400
To: <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Subject: Is it necessary to run secondary namenode when starting HDFS?

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,