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https://issues.apache.org/jira/browse/MAPREDUCE-1831?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12969589#action_12969589
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Scott Chen commented on MAPREDUCE-1831:
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I have remove the dependency of MAPREDUCE-1861. This patch does chooseTarget
for parity file. This does not need MAPREDUCE-1861.
I will also rebase the patch in MAPREDUCE-1861.
> 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
>
>
> 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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