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Message-ID: <1211150042.1251418741835.JavaMail.jira@brutus>
Date: Thu, 27 Aug 2009 17:19:01 -0700 (PDT)
From: "Jitendra Nath Pandey (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Subject: [jira] Commented: (HDFS-15) All replicas of a block end up on only
 1 rack
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    [ https://issues.apache.org/jira/browse/HDFS-15?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12748624#action_12748624 ] 

Jitendra Nath Pandey commented on HDFS-15:
------------------------------------------

Patch updated with "topology.script.file.name"

> All replicas of a block end up on only 1 rack
> ---------------------------------------------
>
>                 Key: HDFS-15
>                 URL: https://issues.apache.org/jira/browse/HDFS-15
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Hairong Kuang
>            Assignee: Jitendra Nath Pandey
>            Priority: Critical
>             Fix For: 0.21.0
>
>         Attachments: HDFS-15.4.patch, HDFS-15.5.patch, HDFS-15.6.patch, HDFS-15.patch, HDFS-15.patch.2, HDFS-15.patch.3
>
>
> HDFS replicas placement strategy guarantees that the replicas of a block exist on at least two racks when its replication factor is greater than one. But fsck still reports that the replicas of some blocks  end up on one rack.
> The cause of the problem is that decommission and corruption handling only check the block's replication factor but not the rack requirement. When an over-replicated block loses a replica due to decomission, corruption, or heartbeat lost, namenode does not take any action to guarantee that remaining replicas are on different racks.
>  

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