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Date: Thu, 20 Jun 2013 14:40:20 +0000 (UTC)
From: "Suresh Srinivas (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12653859.1371705314573.148819.1371739220613@arcas>
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Subject: [jira] [Commented] (HDFS-4921) Create a web page to display the
 namenode features and whether they are turned on or off
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    [ https://issues.apache.org/jira/browse/HDFS-4921?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13689288#comment-13689288 ] 

Suresh Srinivas commented on HDFS-4921:
---------------------------------------

bq. how about just serving up a (pretty printed) piece of JSON targeted at machines rather than people
That is what JMX and JMX+http does. But having a webpage will help as well.
                
> Create a web page to display the namenode features and whether they are turned on or off
> ----------------------------------------------------------------------------------------
>
>                 Key: HDFS-4921
>                 URL: https://issues.apache.org/jira/browse/HDFS-4921
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>    Affects Versions: 3.0.0
>            Reporter: Suresh Srinivas
>
> The only way to determine a feature is turned on or off is to look at namenode logs or configuration. Some times when features change/modified (short circuit for example), the corresponding log message changes or goes from info to debug etc. Logs are not a reliable way to programmatically, for example in tests, to determine if a feature is turned on/off.
> Also when debugging issues, routinely I have to ask for configuration to determine if the feature is turned on or off and hope that the configuration provided is the correct one loaded in the namenode.
> While namenode does provide config it has loaded over http, some times either due to poor documentation or lack of understanding of configuration mechanism, people may not be able to determine the state of the feature. I propose adding a web page that shows all that we print today in the logs, that feature status and the corresponding configuration values and feature status. This should also be made available over JMX and JMX http, just like all the other namenode webUI info, so that scripts and other programs can consume it.

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