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Date: Tue, 24 Sep 2013 18:00:06 +0000 (UTC)
From: "Colin Patrick McCabe (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12669627.1379670908176.10877.1380045606335@arcas>
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Subject: [jira] [Commented] (HDFS-5237) Get rid of nodes' registration names
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    [ https://issues.apache.org/jira/browse/HDFS-5237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13776568#comment-13776568 ] 

Colin Patrick McCabe commented on HDFS-5237:
--------------------------------------------

I'm not so sure that we need to remove this, now.  If it's heavily used in unit tests, and also used by end-users in certain configurations, it's going to be an uphill battle.

Validating it *sounds* like a good idea, but in practice it's going to add up to failing DN registrations if the reported hostname can't be resolved, which doesn't seem that friendly.  DNS is sometimes unreliable like any other network service, after all.

Why don't we add some JavaDoc to DatanodeID explaining the reasons why hostName may in fact not be a real host name?

I also wonder why we need {{DatanodeID#peerHostName}}.  It doesn't seem to be used anywhere, and it definitely muddies the waters in that class.
                
> Get rid of nodes' registration names
> ------------------------------------
>
>                 Key: HDFS-5237
>                 URL: https://issues.apache.org/jira/browse/HDFS-5237
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Junping Du
>             Fix For: 3.0.0
>
>         Attachments: HDFS-5237.patch
>
>
> Per discussion in HDFS-5208 and may be some other discussions before, Node's registration name is pretty confusing and shouldn't be used in production environment as topology resolving issues. So we remove related configuration dfs.datanode.hostname or its old one "slave.host.name".

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