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From "Amar Kamat (JIRA)" <j...@apache.org>
Subject [jira] Resolved: (HADOOP-5377) Inefficient jobtracker history file layout
Date Tue, 03 Mar 2009 04:02:56 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-5377?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Amar Kamat resolved HADOOP-5377.
--------------------------------

    Resolution: Duplicate

Nick, HADOOP-4670 is opened to address the same.

> Inefficient jobtracker history file layout
> ------------------------------------------
>
>                 Key: HADOOP-5377
>                 URL: https://issues.apache.org/jira/browse/HADOOP-5377
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>         Environment: This is at least a problem on 0.15.
>            Reporter: Nick Rettinghouse
>
> Storing too many files in a single directory slows things down tremendously and in this
case, makes the grid just a bit more difficult to manage.  On our jobtrackers, even with a
45 day purge cycle, we see hundreds of thousands of files in logs/hadoop/history.  The following
is an example:
> pchdm01.ypost.re1: logs/hadoop/history - 1,176,927 files!
> This is the time(1) output of the `ls | wc -l`
> real    0m56.042s
> user    0m28.702s
> sys     0m1.794s
> Note that this was the second time I ran this filecount. The first run took more than
4 minutes of real time.
> ===========================================
> My recommended solution is that the Hadoop team store these files in the following structure:
>     history/2008/08/19
>     history/2008/08/20
>     history/2008/08/21
> Using this structure gives us 2 important things: consistently good performance and the
ability to easily delete or archive old files.  
> If we expect a Hadoop cluster to process hundreds of thousands of jobs per day, then
we may want to break it down by
> hour like this:
>     history/2008/08/19/00
>     history/2008/08/19/01
>      ...
>     history/2008/08/19/22
>     history/2008/08/19/23

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