[
https://issues.apache.org/jira/browse/HADOOP-12041?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Kai Zheng updated HADOOP-12041:
-------------------------------
Description:
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.
was:
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 re-implement the underlying facilities for the Java RS coders,
getting rid of existing {{GaliosField}} from HDFS-RAID. Based on this work,
Java RS coders will be re-implemented easily as well to resolve related issues.
> 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
>
> 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
