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From "Kai Zheng (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-7345) Local Reconstruction Codes (LRC)
Date Tue, 04 Nov 2014 06:45:33 GMT
Kai Zheng created HDFS-7345:

             Summary: Local Reconstruction Codes (LRC)
                 Key: HDFS-7345
                 URL: https://issues.apache.org/jira/browse/HDFS-7345
             Project: Hadoop HDFS
          Issue Type: Sub-task
    Affects Versions: HDFS-EC
            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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