-Re: Is it necessary to run secondary namenode when starting HDFS?
Harsh J 2012-12-17, 17:09
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 $HADOOP_CONF_DIR start namenode
> "$bin"/hadoop-daemons.sh --config $HADOOP_CONF_DIR start datanode
> "$bin"/hadoop-daemons.sh --config $HADOOP_CONF_DIR --hosts masters start
> 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,