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https://issues.apache.org/jira/browse/HADOOP-12041?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15131408#comment-15131408
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Kai Zheng commented on HADOOP-12041:
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Thanks [~zhz] and [~walter.k.su] for the review and commit!! Wish it to be much
useful for EC users and worth the much time I spent on it. :)
bq. I think we should also file a follow-on JIRA to make the tests more
systematic, like what Rui did for TestDFSStripedOutputStreamWithFailure.
I guess you meant [~demongaorui]. Sounds good to have systematic tests for the
coders. Compatible tests with ISA-L coder will be provided in HADOOP-12540. For
this follow-on and the follow-on works discussed in this issue, [~lirui], would
you help with these? Thanks.
> Implement another Reed-Solomon coder in pure Java
> -------------------------------------------------
>
> Key: HADOOP-12041
> URL: https://issues.apache.org/jira/browse/HADOOP-12041
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: Kai Zheng
> Fix For: 3.0.0
>
> Attachments: HADOOP-12041-v1.patch, HADOOP-12041-v2.patch,
> HADOOP-12041-v3.patch, HADOOP-12041-v4.patch, HADOOP-12041-v5.patch,
> HADOOP-12041-v6.patch, HADOOP-12041-v7.patch, HADOOP-12041-v8.patch
>
>
> Currently existing Java RS coders based on {{GaloisField}} implementation
> have some drawbacks or limitations:
> * The decoder computes not really erased units unnecessarily (HADOOP-11871);
> * The decoder requires parity units + data units order for the inputs in the
> decode API (HADOOP-12040);
> * Need to support or align with native erasure coders regarding concrete
> coding algorithms and matrix, so Java coders and native coders can be easily
> swapped in/out and transparent to HDFS (HADOOP-12010);
> * It's unnecessarily flexible but incurs some overhead, as HDFS erasure
> coding is totally a byte based data system, we don't need to consider other
> symbol size instead of 256.
> This desires to implement another RS coder in pure Java, in addition to the
> existing {{GaliosField}} from HDFS-RAID. The new Java RS coder will be
> favored and used by default to resolve the related issues. The old HDFS-RAID
> originated coder will still be there for comparing, and converting old data
> from HDFS-RAID systems.
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