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Date: Wed, 8 Jul 2015 05:06:05 +0000 (UTC)
From: "Walter Su (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-8731) Erasure coding: For a small file
 missing and under replicated ec-block calculation is incorrect
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    [ https://issues.apache.org/jira/browse/HDFS-8731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14617980#comment-14617980 ] 

Walter Su commented on HDFS-8731:
---------------------------------

Is it duplicated with HDFS-8563?

> Erasure coding: For a small file missing and under replicated ec-block calculation is incorrect 
> ------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-8731
>                 URL: https://issues.apache.org/jira/browse/HDFS-8731
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: J.Andreina
>            Assignee: J.Andreina
>
> Write a small file (whose replica detail would be : one data replica and 3 parity replicas .)
> Now :
> 	totalReplicasPerBlock = 4 
> 	targetFileReplication = 9 (calculated based on default RS-6-3 schema)
> Hence the small file ec-blocks is calculated as always missing and underreplicated. which is wrong... 
> {code}
> targetFileReplication = (short) (ecSchema.getNumDataUnits() + ecSchema.getNumParityUnits());
> {code}
> {code}
>       // count missing replicas / under replicated blocks
>       if (totalReplicasPerBlock < targetFileReplication && totalReplicasPerBlock > 0) {
>         res.missingReplicas += (targetFileReplication - totalReplicasPerBlock);
> 	res.numUnderReplicatedBlocks += 1;
> {code}


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