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Posted to hdfs-issues@hadoop.apache.org by "Andrew Wang (JIRA)" <ji...@apache.org> on 2016/10/07 20:34:20 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=15556169#comment-15556169 ]
Andrew Wang commented on HDFS-3544:
-----------------------------------
The other note is that we have a JIRA to add LRC support (HDFS-7345) but it's patent encumbered by Microsoft.
> 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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