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Date: Fri, 15 Jun 2007 11:23:26 -0700 (PDT)
From: "Koji Noguchi (JIRA)" <jira@apache.org>
To: hadoop-dev@lucene.apache.org
Subject: [jira] Issue Comment Edited: (HADOOP-1491) After successful distcp,
 couple of checksum error files
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    [ https://issues.apache.org/jira/browse/HADOOP-1491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12505336 ] 

Koji Noguchi edited comment on HADOOP-1491 at 6/15/07 11:21 AM:
----------------------------------------------------------------

To confirm Dhruba and Raghu's analysis, 
I inserted one debug print statement inside DFSClient.newBackupFile to print out the "result" and "src".

On one node, two mappers started (almost) at the same time by the distcp.
There were definitely clashing on the temporary file names.  
Attaching the two userlogs.


Picked files from the clashing and dfs -get from source and target cluster. ls -l showed 

-rw-r--r--  1 knoguchi users 133142 Jun 15 10:46 part-270-source
-rw-r--r--  1 knoguchi users 133848 Jun 15 10:47 part-270-target
-rw-r--r--  1 knoguchi users 133848 Jun 15 10:48 part-277-source
-rw-r--r--  1 knoguchi users 133848 Jun 15 10:47 part-277-target

After the copy, part-270 file was corrupted.


 was:
To confirm Dhruba and Raghu's analysis, 
I inserted one debug print statement inside DFSClient.newBackupFile to print out the "result" and "src".

On one node, two mappers started (almost) at the same time by the distcp.
There were difinitely clashing on the temporary file names.  
Attaching the two userlogs.


Picked files from the clashing and dfs -get from source and target cluster. ls -l showed 

-rw-r--r--  1 knoguchi users 133142 Jun 15 10:46 part-270-source
-rw-r--r--  1 knoguchi users 133848 Jun 15 10:47 part-270-target
-rw-r--r--  1 knoguchi users 133848 Jun 15 10:48 part-277-source
-rw-r--r--  1 knoguchi users 133848 Jun 15 10:47 part-277-target

After the copy, part-270 file was corrupted.


> After successful distcp, couple of checksum error files
> -------------------------------------------------------
>
>                 Key: HADOOP-1491
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1491
>             Project: Hadoop
>          Issue Type: Bug
>          Components: util
>    Affects Versions: 0.12.3
>            Reporter: Koji Noguchi
>         Attachments: mapper1.txt
>
>
> Tried copying 700,000 files  with distcp. 8 mappers per node.  Single dfs.client.buffer.dir.
> Distcp ran on 25 nodes mapreduce.
> Couple of tasks failed, but job was successful. 
> When checked, 12  files were corrupted. (Checksum error)
> This is repeatable.
> I'll add more information as we find.

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