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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?
Thank you very much!

It is now clear for me, that in development mode I'll not start secondary
namenode.But in production it's better to have it.
Thanks!

Regards,
Ivan
2012/12/17 Harsh J <[EMAIL PROTECTED]>

> The SecondaryNameNode is necessary for automatic maintenance in
> long-running clusters (read: production), but is not necessary for,
> nor tied into the basic functions/operations of HDFS.
>
> On 1.x, you can remove the script's startup of SNN by removing its
> host entry from the conf/masters file.
> On 2.x, you can selectively start the NN and DNs by using the
> hadoop-daemon.sh script commands.
>
> On Mon, Dec 17, 2012 at 10:34 PM, Ivan Ryndin <[EMAIL PROTECTED]> wrote:
> > 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,
> >
>
>
>
> --
> Harsh J
>

--

Best regards,
Ivan P. Ryndin,
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB