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https://issues.apache.org/jira/browse/HDFS-7891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14496882#comment-14496882
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Zhe Zhang commented on HDFS-7891:
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Thanks for the patch Walter! The patch looks good overall. Please find my
review below.
Logic:
# I think the current flow is functionally correct. But {{maxNodesPerRack}} no
longer denotes the maximum nodes to be allocated per rack, making the code less
readable. Right now {{chooseTargetInOrder}} treats {{maxNodesPerRack}} as the
number of replicas to allocate to each rack _in the first round_.
# If we simply let {{getMaxNodesPerRack()}} return the ceiling of
{{totalNumOfReplicas/numOfRacks}}, like {{(totalNumOfReplicas - 1) / numOfRacks
+ 1}}, then do not override {{chooseTargetInOrder()}}, can we get the right
distribution we want?
Nits:
# Override annotation missing in
{{BlockPlacementPolicyRackFaultTolarent#chooseTargetInOrder}}
# Could remove the empty constructor of
{{BlockPlacementPolicyRackFaultTolarent}}
# {{chooseOnce}| needs some Javadoc.
[~szetszwo]: Since this is targeted for trunk now, it would be great if you can
review the patch as well. Thanks!
> A block placement policy with best rack failure tolerance
> ---------------------------------------------------------
>
> Key: HDFS-7891
> URL: https://issues.apache.org/jira/browse/HDFS-7891
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: namenode
> Reporter: Walter Su
> Assignee: Walter Su
> Priority: Minor
> Attachments: HDFS-7891.005.dup.patch, HDFS-7891.005.patch
>
>
> a block placement policy tries its best to place replicas to most racks.
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