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https://issues.apache.org/jira/browse/HBASE-5509?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13230810#comment-13230810
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Lars Hofhansl commented on HBASE-5509:
--------------------------------------

Ran a first few tests on a table with 16 regions and two column families. 
(small cluster with 6 datanodes/regionservers)
Snapshot took about two times as long as distcp of the same data (which 
surprised me).
Interestingly distcp used 48 mappers while Snapshot used 16 mappers.
                
> MR based copier for copying HFiles (trunk version)
> --------------------------------------------------
>
>                 Key: HBASE-5509
>                 URL: https://issues.apache.org/jira/browse/HBASE-5509
>             Project: HBase
>          Issue Type: Sub-task
>          Components: documentation, regionserver
>            Reporter: Karthik Ranganathan
>            Assignee: Lars Hofhansl
>             Fix For: 0.94.0, 0.96.0
>
>         Attachments: 5509-v2.txt, 5509.txt
>
>
> This copier is a modification of the distcp tool in HDFS. It does the 
> following:
> 1. List out all the regions in the HBase cluster for the required table
> 2. Write the above out to a file
> 3. Each mapper 
>    3.1 lists all the HFiles for a given region by querying the regionserver
>    3.2 copies all the HFiles
>    3.3 outputs success if the copy succeeded, failure otherwise. Failed 
> regions are retried in another loop
> 4. Mappers are placed on nodes which have maximum locality for a given region 
> to speed up copying

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