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https://issues.apache.org/jira/browse/HADOOP-11794?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15044105#comment-15044105
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Mithun Radhakrishnan commented on HADOOP-11794:
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[~yzhangal]: Thank you, sir. Please do. Hive has kept me busy enough not to
devote time here. I'd be happy to review your work.
I had a patch a couple of years ago which split files on block-boundaries,
copied them over, and then stitched them together using
{{DistributedFileSystem.concat()}} in a reduce-step. If I can find the patch,
I'll ping it to you, but it's not terribly hard to do this from scratch. The
prototype had very promising performance.
I look forward to your solution.
> distcp can copy blocks in parallel
> ----------------------------------
>
> Key: HADOOP-11794
> URL: https://issues.apache.org/jira/browse/HADOOP-11794
> Project: Hadoop Common
> Issue Type: Improvement
> Components: tools/distcp
> Affects Versions: 0.21.0
> Reporter: dhruba borthakur
> Assignee: Mithun Radhakrishnan
> Attachments: MAPREDUCE-2257.patch
>
>
> The minimum unit of work for a distcp task is a file. We have files that are
> greater than 1 TB with a block size of 1 GB. If we use distcp to copy these
> files, the tasks either take a long long long time or finally fails. A better
> way for distcp would be to copy all the source blocks in parallel, and then
> stich the blocks back to files at the destination via the HDFS Concat API
> (HDFS-222)
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