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https://issues.apache.org/jira/browse/HDFS-385?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13426495#comment-13426495
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Tsz Wo (Nicholas), SZE commented on HDFS-385:
---------------------------------------------
Thanks for the update. Some comments:
- Add "srcPath" as a parameter of FSNamesystem.chooseDatanode(..) and then pass
"path" in NamenodeWebHdfsMethods.chooseDatanode(..).
- Add the following comments to FSNamesystem.computeReplicationWorkForBlock(..)
as in the original patch.
{code}
// choose replication targets: NOT HOLDING THE GLOBAL LOCK
+ // It is costly to extract the filename for which chooseTargets is called,
+ // so for now we pass in the Inode itself.
{code}
- Please remove the tabs since we do not use tabs in Hadoop. Indentation is
two spaces.
Please also run all the unit tests (ant test-core) since Jenkins doesn't work
for branch-1. Thanks!
> Design a pluggable interface to place replicas of blocks in HDFS
> ----------------------------------------------------------------
>
> Key: HDFS-385
> URL: https://issues.apache.org/jira/browse/HDFS-385
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Fix For: 0.21.0
>
> Attachments: BlockPlacementPluggable.txt,
> BlockPlacementPluggable2.txt, BlockPlacementPluggable3.txt,
> BlockPlacementPluggable4.txt, BlockPlacementPluggable4.txt,
> BlockPlacementPluggable5.txt, BlockPlacementPluggable6.txt,
> BlockPlacementPluggable7.txt, blockplacementpolicy-branch-1-win.patch,
> blockplacementpolicy-branch-1.patch,
> blockplacementpolicy2-branch-1-win.patch,
> blockplacementpolicy2-branch-1.patch, rat094.txt
>
>
> The current HDFS code typically places one replica on local rack, the second
> replica on remote random rack and the third replica on a random node of that
> remote rack. This algorithm is baked in the NameNode's code. It would be nice
> to make the block placement algorithm a pluggable interface. This will allow
> experimentation of different placement algorithms based on workloads,
> availability guarantees and failure models.
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