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Date: Mon, 21 Jul 2008 15:55:31 -0700 (PDT)
From: "Ari Rabkin (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Updated: (HADOOP-9) mapred.local.dir  temp dir. space
 allocation limited by smallest area
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     [ https://issues.apache.org/jira/browse/HADOOP-9?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ari Rabkin updated HADOOP-9:
----------------------------

    Attachment: hadoop9.patch

Patch fixing this issue.

> mapred.local.dir  temp dir. space allocation limited by smallest area
> ---------------------------------------------------------------------
>
>                 Key: HADOOP-9
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>         Environment: all
>            Reporter: Paul Baclace
>            Assignee: Ari Rabkin
>         Attachments: hadoop9.patch
>
>
> When mapred.local.dir is used to specify multiple  temp dir. areas, space allocation limited by smallest area because the temp dir. selection algorithm is "round robin starting from a randomish point".   When round robin is used with approximately constant sized chunks, the smallest area runs out of space first, and this is a fatal error. 
> Workaround: only list local fs dirs in mapred.local.dir with similarly-sized available areas.
> I wrote a patch to JobConf (currenly being tested) which uses df to check available space (once a minute or less often) and then uses an efficient roulette selection to do allocation weighted by magnitude of available space. 

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