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This article mainly explains "what is the method of deleting hadoop2.2 cluster nodes". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the method of deleting hadoop2.2 cluster nodes".

1. Node deletion

1) modify the directory of conf/hdfs-site.xml file and excludes file. As follows:

Dfs.hosts.exclude / home/hadoop/hadoop-2.2.0/etc/hadoop/excludes Names a file that contains a list of hosts that are not permitted to connect to the namenode. The full pathname of the file must be specified. If the value is empty, no hosts are excluded.

2) specify the machines to be removed from the shelves in the excludes file, such as:

Slave1

3) refresh the configuration and execute the following command:

Bin/hadoop dfsadmin-refreshNodes

4) View status

Use the command on the command line: bin/hadoop dfsadmin-report or check in the browser: http://XXXXX:50070/dfshealth.jsp appears in the following state, while the number of Blocks is decreasing. Live Nodes: 10 (Decommissioned: 0) Dead Nodes: 0 (Decommissioned: 0) Decommissioning Nodes: 2 Number of Under-Replicated Blocks: 106106

5) Edit the excludes file again

Once the machine is off the shelf, they can be removed from the excludes file

Log in to the machine to be taken off the shelf and you will find that the DataNode process is gone, but the TaskTracker still exists and needs to be handled manually

6)。 Problems encountered:

(1) when the configuration is refreshed, the number of block remains unchanged. Possible reason: safe mode

Bin/hadoop dfsadmin-safemode leave

(2) the number of block has been decreasing, but since then it has not changed. Possible reason: there may be a problem with the password-free login of the cluster. Check it.

3. Additional: password-free login

At the same time, pay attention to the issue of authority.

After ssh configuration is successful, Are you sure you want to continue connecting (yes/no) appears when the hadoop node is started.

Enter yes

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