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https://issues.apache.org/jira/browse/HDFS-9963?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kai Sasaki resolved HDFS-9963.
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Resolution: Invalid
[~brahmareddy] I think so too. I closed. Thanks!
> CLONE - Erasure Coding Support inside HDFS
> ------------------------------------------
>
> Key: HDFS-9963
> URL: https://issues.apache.org/jira/browse/HDFS-9963
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: dragon
> Assignee: Zhe Zhang
> Fix For: 3.0.0
>
>
> Erasure Coding (EC) can greatly reduce the storage overhead without sacrifice
> of data reliability, comparing to the existing HDFS 3-replica approach. For
> example, if we use a 10+4 Reed Solomon coding, we can allow loss of 4 blocks,
> with storage overhead only being 40%. This makes EC a quite attractive
> alternative for big data storage, particularly for cold data.
> Facebook had a related open source project called HDFS-RAID. It used to be
> one of the contribute packages in HDFS but had been removed since Hadoop 2.0
> for maintain reason. The drawbacks are: 1) it is on top of HDFS and depends
> on MapReduce to do encoding and decoding tasks; 2) it can only be used for
> cold files that are intended not to be appended anymore; 3) the pure Java EC
> coding implementation is extremely slow in practical use. Due to these, it
> might not be a good idea to just bring HDFS-RAID back.
> We (Intel and Cloudera) are working on a design to build EC into HDFS that
> gets rid of any external dependencies, makes it self-contained and
> independently maintained. This design lays the EC feature on the storage type
> support and considers compatible with existing HDFS features like caching,
> snapshot, encryption, high availability and etc. This design will also
> support different EC coding schemes, implementations and policies for
> different deployment scenarios. By utilizing advanced libraries (e.g. Intel
> ISA-L library), an implementation can greatly improve the performance of EC
> encoding/decoding and makes the EC solution even more attractive. We will
> post the design document soon.
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