CODEWITHSUNDEEP
hadoophdfs
Abbas Gadhia
Abbas Gadhia

Reputation: 15128

Hadoop - Restart datanode and tasktracker

I want to bring down a single datanode and tasktracker, so that some new changes that i've made in my mapred-site.xml take effect, such as mapred.reduce.child.java.opts etc. How do I do that? However I don't want to bring down the whole cluster since i have active jobs running.

Also, how can that be done ensuring that the namenode does not copy the relevant data blocks of a "temporarily down" datanode onto another node

Upvotes: 15

Views: 49200

Answers (3)

Joel Bondurant
Joel Bondurant

Reputation: 883

In Hadoop 2.7.2, tasktracker is long gone, to manually restart services out on slaves:

yarn-daemon.sh stop nodemanager
hadoop-daemon.sh stop datanode
hadoop-daemon.sh start datanode
yarn-daemon.sh start nodemanager

Upvotes: 10

user2486495
user2486495

Reputation: 1729

To stop

You can stop the DataNodes and TaskTrackers from NameNode's hadoop bin directory.

./hadoop-daemon.sh stop tasktracker 
./hadoop-daemon.sh stop datanode

So this script checks for slaves file in conf directory of hadoop to stop the DataNodes and same with the TaskTracker.

To start

Again this script checks for slaves file in conf directory of hadoop to start the DataNodes and TaskTrackers.

./hadoop-daemon.sh start tasktracker
./hadoop-daemon.sh start datanode

Upvotes: 15

Abbas Gadhia
Abbas Gadhia

Reputation: 15128

Ssh into the datanode/tasktracker machine and cd into the bin directory of hadoop.

Invoke

./hadoop-daemon.sh stop tasktracker

./hadoop-daemon.sh stop datanode

./hadoop-daemon.sh start datanode

./hadoop-daemon.sh start tasktracker

I'm not sure if restarting the tasktracker is required for the changes in mapred-site.xml to take effect. Please leave a comment so that i can correct my answer if needed

Upvotes: 4

Related Questions