He Xiaoqiao created HDFS-14563:
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Summary: 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: He Xiaoqiao
Assignee: He Xiaoqiao
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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