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https://issues.apache.org/jira/browse/HDFS-7345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14207572#comment-14207572
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Kai Zheng commented on HDFS-7345:
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Thanks [~andrew.wang] for the escalating.
> Local Reconstruction Codes (LRC)
> --------------------------------
>
> Key: HDFS-7345
> URL: https://issues.apache.org/jira/browse/HDFS-7345
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: Kai Zheng
>
> HDFS-7285 proposes to support Erasure Coding inside HDFS, supports multiple
> Erasure Coding codecs via pluggable framework and implements Reed Solomon
> code by default. This is to support a more advanced coding mechanism, Local
> Reconstruction Codes (LRC). As discussed in the paper
> (https://www.usenix.org/system/files/conference/atc12/atc12-final181_0.pdf),
> LRC reduces the number of erasure coding fragments that need to be read when
> reconstructing data fragments that are offline, while still keeping the
> storage overhead low. The important benefits of LRC are that it reduces the
> bandwidth and I/Os required for repair reads over prior codes, while still
> allowing a significant reduction in storage overhead. Intel ISA library also
> supports LRC in its update and can also be leveraged. The implementation
> would also consider how to distribute the calculating of local and global
> parity blocks to other relevant DataNodes.
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