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https://issues.apache.org/jira/browse/HDFS-9005?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14998911#comment-14998911
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Ming Ma commented on HDFS-9005:
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[~jmeagher] provided some input from admins point of view. The existing
refreshNodes has some limitations.
* It requires admins update the hosts/excludes files on each NN local machine
and then send refreshNodes RPC to NN. In some cases, it is much easier to
manage if any remote machine(with admin privilege) can directly ask NN to
decommission some nodes via RPC.
* hosts/excludes files inconsistency across NNs. Having each NN has its own
copy of the files couple introduces possible inconsistency of the files.
* RefreshNodes efficiency. For a large cluster, reloading the whole files for
all DNs just to update the property of few DNs isn't efficient.
So we wonder if we should take this opportunity to look into another approach
(might have been discussed before):
* Add new RPC to ClientProtocol to allow dfsadmin to set properties for
specific DNs, that could include decommission, upgrade domain, etc.
* The request will be persisted to an extensible state store. It could be
leveldb, fsimage/edit log, etc. Only active NN can update the state store. NNs
will read from state store at start up time. Standby NN will get notified on
state store change.
> Provide support for upgrade domain script
> -----------------------------------------
>
> Key: HDFS-9005
> URL: https://issues.apache.org/jira/browse/HDFS-9005
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Ming Ma
>
> As part of the upgrade domain feature, we need to provide a mechanism to
> specify upgrade domain for each datanode. One way to accomplish that is to
> allow admins specify an upgrade domain script that takes DN ip or hostname as
> input and return the upgrade domain. Then namenode will use it at run time to
> set {{DatanodeInfo}}'s upgrade domain string. The configuration can be
> something like:
> {noformat}
> <property>
> <name>dfs.namenode.upgrade.domain.script.file.name</name>
> <value>/etc/hadoop/conf/upgrade-domain.sh</value>
> </property>
> {noformat}
> just like topology script,
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