[jira] [Commented] (MAPREDUCE-1831) BlockPlacement policy for RAID

["Hudson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1831?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13017000#comment-13017000 ] 

Hudson commented on MAPREDUCE-1831:
-----------------------------------

Integrated in Hadoop-Mapreduce-trunk #643 (See [https://hudson.apache.org/hudson/job/Hadoop-Mapreduce-trunk/643/])
    

> BlockPlacement policy for RAID
> ------------------------------
>
>                 Key: MAPREDUCE-1831
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1831
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: contrib/raid
>    Affects Versions: 0.23.0
>            Reporter: Scott Chen
>            Assignee: Scott Chen
>             Fix For: 0.23.0
>
>         Attachments: MAPREDUCE-1831-v2.txt, MAPREDUCE-1831.20100610.txt, MAPREDUCE-1831.txt, MAPREDUCE-1831.v1.1.txt, test.result
>
>
> Raid introduce the new dependency between blocks within a file.
> The blocks help decode each other. Therefore we should avoid put them on the same machine.
> The proposed BlockPlacementPolicy does the following
> 1. When writing parity blocks, it avoid the parity blocks and source blocks sit together.
> 2. When reducing replication number, it deletes the blocks that sits with other dependent blocks.
> 3. It does not change the way we write normal files. It only has different behavior when processing raid files.

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