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From "Haohui Mai (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6982) nntop: top­-like tool for name node users
Date Fri, 05 Sep 2014 23:02:30 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6982?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14123750#comment-14123750
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Haohui Mai commented on HDFS-6982:
----------------------------------

This is a nice feature, thanks for [~maysamyabandeh]!

I have a couple questions:

# What are the minimal changes in the hadoop side to enable this functionality? If nntop goes
for the second architecture, does it mean that there is no code changes required in the hadoop
side?
# Should rolling window reside in the NN? I wonder whether the code should simply publish
the metrics to Ganglia / Nagios, etc., and let these framework take care of the aggregation,
plotting, etc.



> nntop: top­-like tool for name node users
> -----------------------------------------
>
>                 Key: HDFS-6982
>                 URL: https://issues.apache.org/jira/browse/HDFS-6982
>             Project: Hadoop HDFS
>          Issue Type: New Feature
>            Reporter: Maysam Yabandeh
>            Assignee: Maysam Yabandeh
>         Attachments: HDFS-6982.patch, HDFS-6982.v2.patch, nntop-design-v1.pdf
>
>
> In this jira we motivate the need for nntop, a tool that, similarly to what top does
in Linux, gives the list of top users of the HDFS name node and gives insight about which
users are sending majority of each traffic type to the name node. This information turns out
to be the most critical when the name node is under pressure and the HDFS admin needs to know
which user is hammering the name node and with what kind of requests. Here we present the
design of nntop which has been in production at Twitter in the past 10 months. nntop proved
to have low cpu overhead (< 2% in a cluster of 4K nodes), low memory footprint (less than
a few MB), and quite efficient for the write path (only two hash lookup for updating a metric).



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