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From "Sanjay Radia (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-12990) Change default NameNode RPC port back to 8020
Date Mon, 22 Jan 2018 18:55:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-12990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16334743#comment-16334743
] 

Sanjay Radia commented on HDFS-12990:
-------------------------------------

For this Jira, I can go either way.
 In this specific case there is a very simple work around for the 2.x customer if he reads
the release notes and adds a config to use his old port number. Anyone going from 2.x to 3.0 should
read the release. However I can see that  other harder cases may come up over the next couple
of months where there isn’t such a convenient workaround. For example we are likely to come
up with new issues when we do upgrade testing and there will be similar debates including
arguments on the importance of supporting rolling upgrade from 2x to 3.0. 
  
 To avoid such debates I suggest we amend our guideline to something of the following lines:
  
 On each new major release,  till a tag such as  “stable” is assigned by the PMC, 
we allow  changes that make the software *compatible with the previous major release, even
if that change breaks compatibility within the major release.* These changes may be for where
we accidentally break compatibility or even when we concisely made a change without fully
understanding or appreciating the impact of the incompatible change.  The PMC will determine
the testing criteria for assigning the stable tag.
  
  
 The above guideline  will reduce such debates during a GA of a Major release.  Further,
users will realize that they need to wait for the stable tag before going production.   One
might argue that a  GA release without a “stable” tag is merely a glorified beta or a
GA-candidate. Yes i agree. Perhaps in this case we may have rushed from beta to GA a little
too early. I think the above forces the PMC to seriously determine GA testing criteria and
 validate whether or they have been met. 

> Change default NameNode RPC port back to 8020
> ---------------------------------------------
>
>                 Key: HDFS-12990
>                 URL: https://issues.apache.org/jira/browse/HDFS-12990
>             Project: Hadoop HDFS
>          Issue Type: Task
>          Components: namenode
>    Affects Versions: 3.0.0
>            Reporter: Xiao Chen
>            Assignee: Xiao Chen
>            Priority: Critical
>         Attachments: HDFS-12990.01.patch
>
>
> In HDFS-9427 (HDFS should not default to ephemeral ports), we changed all default ports
to ephemeral ports, which is very appreciated by admin. As part of that change, we also modified
the NN RPC port from the famous 8020 to 9820, to be closer to other ports changed there.
> With more integration going on, it appears that all the other ephemeral port changes
are fine, but the NN RPC port change is painful for downstream on migrating to Hadoop 3. Some
examples include:
> # Hive table locations pointing to hdfs://nn:port/dir
> # Downstream minicluster unit tests that assumed 8020
> # Oozie workflows / downstream scripts that used 8020
> This isn't a problem for HA URLs, since that does not include the port number. But considering
the downstream impact, instead of requiring all of them change their stuff, it would be a
way better experience to leave the NN port unchanged. This will benefit Hadoop 3 adoption
and ease unnecessary upgrade burdens.
> It is of course incompatible, but giving 3.0.0 is just out, IMO it worths to switch the
port back.



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