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https://issues.apache.org/jira/browse/HDFS-4885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13799572#comment-13799572
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Tsz Wo (Nicholas), SZE commented on HDFS-4885:
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- In BlockPlacementStatusDefault, "misReplicatedNum" may be misleading since it
is the number of racks the block should be additionally replicated to. Why
don't we store both requiredRacks and currentRacks?
- hasMisplacement and getMisreplacementDescription may also be misleading since
there may not be any misplacement at all but it does not satisfy the block
placement policy. How about renaming hasMisplacement to "isGoodPlacement" or
"isPlacementPolicySatisfied", and renaming getMisreplacementDescription to
"getErrorDescription" or "getErrorMessage".
- In BlockPlacementPolicyDefault.verifyBlockPlacement(..),
let X = Math.min(2, numberOfReplicas). Then, X <= 2.
We also have numRacks >= 2 since if(numRacks <= 1) return.
As a result, X <= numRacks (i.e. Math.min(X, numRacks) == X) for any case.
So we could simplify the code to
{code}
int minRacks = Math.min(2, numberOfReplicas);
{code}
- Please remove the HdfsFileStatus imports in BlockPlacementPolicy and
BlockPlacementPolicyDefault.
- In NamenodeFsck, let's use targetFileReplication for file.getReplication().
> Update verifyBlockPlacement() API in BlockPlacementPolicy
> ---------------------------------------------------------
>
> Key: HDFS-4885
> URL: https://issues.apache.org/jira/browse/HDFS-4885
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Junping Du
> Assignee: Junping Du
> Labels: BlockPlacementPolicy
> Attachments: HDFS-4885.patch, HDFS-4885-v2.patch, HDFS-4885-v3.patch,
> HDFS-4885-v4.patch
>
>
> verifyBlockPlacement() has unused parameter -srcPath as its responsibility
> just verify single block rather than files under a specific path. Also the
> return value (int) does not make sense as the violation of block placement
> has other case than number of racks, so boolean value should be better.
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