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https://issues.apache.org/jira/browse/HDFS-14563?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16978954#comment-16978954
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Xiaoqiao He commented on HDFS-14563:
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Thanks [~weichiu] pick up this JIRA and sorry for no update for long time.
Please feel free to commit other PRs. And I will rebase this one and re-upload
when have time. Thanks again.
> Enhance interface about recommissioning/decommissioning
> -------------------------------------------------------
>
> Key: HDFS-14563
> URL: https://issues.apache.org/jira/browse/HDFS-14563
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client, namenode
> Reporter: Xiaoqiao He
> Assignee: Xiaoqiao He
> Priority: Major
> Labels: decommission
> Attachments: HDFS-14563.001.patch, HDFS-14563.002.patch, mt_mode-2.txt
>
>
> In current implementation, if we need to decommissioning or recommissioning
> one datanode, the only way is add the datanode to include or exclude file
> under namenode configuration path then execute command `bin/hadoop dfsadmin
> -refreshNodes` and trigger namenode to reload include/exclude and start to
> recommissioning or decommissioning datanode.
> The shortcomings of this approach is that:
> a. namenode reload include/exclude configuration file from devices, if I/O
> load is high, handler may be blocked.
> b. namenode has to process every datnodes in include and exclude
> configurations, if there are many datanodes (very common for large cluster)
> pending to process, namenode will be hung for hundred seconds to wait
> recommision/decommision finish at the worst since holding write lock.
> I think we should expose one lightweight interface to support recommissioning
> or decommissioning single datanode, thus we can operate datanode using
> dfsadmin more smooth.
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