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Posted to hdfs-issues@hadoop.apache.org by "liuruoxi (JIRA)" <ji...@apache.org> on 2014/10/23 17:35:36 UTC

[jira] [Commented] (HDFS-3544) Ability to use SimpleRegeratingCode to fix missing blocks

    [ https://issues.apache.org/jira/browse/HDFS-3544?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14181475#comment-14181475 ] 

liuruoxi commented on HDFS-3544:
--------------------------------

Hey，i m a new learner about hadoop and hdfs-raid，i got a question ，why doesnt the raid codes be merged into the trunk since release 2.0.2？

> Ability to use SimpleRegeratingCode to fix missing blocks
> ---------------------------------------------------------
>
>                 Key: HDFS-3544
>                 URL: https://issues.apache.org/jira/browse/HDFS-3544
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: contrib/raid
>            Reporter: dhruba borthakur
>
> ReedSolomon encoding (n, k) has n storage nodes and can tolerate n-k failures. Regenerating a block needs to access k blocks. This is a problem when n and k are large. Instead, we can use simple regenerating codes (n, k, f) that does first does ReedSolomon (n,k) and then does XOR with f stripe size. Then, a single disk failure needs to access only f nodes and f can be very small.



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