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https://issues.apache.org/jira/browse/HDFS-503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12917481#action_12917481
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Ramkumar Vadali commented on HDFS-503:
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@shravankumar, to get a basic idea of HDFS RAID, you can read up Dhruba's blog
post
http://hadoopblog.blogspot.com/2009/08/hdfs-and-erasure-codes-hdfs-raid.html
If you need this for demo purposes, could you use the current hadoop trunk? I
am not sure about the exact date of the next release.
To use RAID, you need to create a configuration file and start the RAID daemon.
You can look for examples in the unit tests, say TestRaidNode.
For further communication, you can contact me directly.
> Implement erasure coding as a layer on HDFS
> -------------------------------------------
>
> Key: HDFS-503
> URL: https://issues.apache.org/jira/browse/HDFS-503
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: contrib/raid
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Fix For: 0.21.0
>
> Attachments: raid1.txt, raid2.txt
>
>
> The goal of this JIRA is to discuss how the cost of raw storage for a HDFS
> file system can be reduced. Keeping three copies of the same data is very
> costly, especially when the size of storage is huge. One idea is to reduce
> the replication factor and do erasure coding of a set of blocks so that the
> over probability of failure of a block remains the same as before.
> Many forms of error-correcting codes are available, see
> http://en.wikipedia.org/wiki/Erasure_code. Also, recent research from CMU has
> described DiskReduce
> https://opencirrus.org/system/files/Gibson-OpenCirrus-June9-09.ppt.
> My opinion is to discuss implementation strategies that are not part of base
> HDFS, but is a layer on top of HDFS.
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