Hadoop - 重新启动datanode和tasktracker

问题描述

我想关闭一个datanode和tasktracker，以便我在mapred-site.xml中做出的一些新更改生效，例如mapred.reduce.child.java.opts等。我如何去做？然而，我不想让整个集群失效，因为我有活动的作业正在运行。

另外，如何确保namenode不会复制相关内容暂时关闭datanode的数据块到另一个节点上

解决方案

停止

您可以从NameNode的hadoop bin目录停止DataNode和TaskTracker。

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

所以此脚本将检查hadoop的 conf 目录中的奴隶文件，以停止DataNode，并且与TaskTracker相同。

开始

此脚本再次检查hadoop的 conf 目录中的奴隶文件启动DataNode和TaskTracker。

  ./ hadoop-daemon.sh start tasktracker 
 ./hado op-daemon.sh启动datanode 
  

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

解决方案

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

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