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Posted to mapreduce-issues@hadoop.apache.org by "liuwei (JIRA)" <ji...@apache.org> on 2014/07/02 16:56:27 UTC

[jira] [Commented] (MAPREDUCE-2257) distcp can copy blocks in parallel

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14049997#comment-14049997 ] 

liuwei commented on MAPREDUCE-2257:
-----------------------------------

since distcp has distcp2, is there a patch exits for distcp2 to copy blocks in parallel?

> distcp can copy blocks in parallel
> ----------------------------------
>
>                 Key: MAPREDUCE-2257
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2257
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: 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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