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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-124) Files still rotting in DFS of latest Hadoop
Date Fri, 07 Apr 2006 17:46:23 GMT
Files still rotting in DFS of latest Hadoop
-------------------------------------------

         Key: HADOOP-124
         URL: http://issues.apache.org/jira/browse/HADOOP-124
     Project: Hadoop
        Type: Bug

  Components: dfs  
 Environment: ~30 node cluster
    Reporter: Bryan Pendleton


DFS files are still rotting.

I suspect that there's a problem with block accounting/detecting identical hosts in the namenode.
I have 30 physical nodes, with various numbers of local disks, meaning that my current 'bin/hadoop
dfs -report" shows 80 nodes after a full restart. However, when I discovered the  problem
(which resulted in losing about 500gb worth of temporary data because of missing blocks in
some of the larger chunks) -report showed 96 nodes. I suspect somehow there were extra datanodes
running against the same paths, and that the namenode was counting those as replicated instances,
which then showed up over-replicated, and one of them was told to delete its local block,
leading to the block actually getting lost.

I will debug it more the next time the situation arises. This is at least the 5th time I've
had a large amount of file data "rot" in DFS since January.

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