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https://issues.apache.org/jira/browse/HDFS-2139?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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zhaoyunjiong updated HDFS-2139:
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Attachment: HDFS-2139.patch
Seems Pritam don't have time to create a patch for Apache.
And I do think use hard link to copy data between pools is a good idea,
so based on the FaceBook's version of FastCopy, I created this patch to copy
files between pools.
Compare to the origin FastCopy, this patch only use hard link to do the copy.
It's a early version, it works on my test cluster which only have 6 datanodes.
Please let me know if I need change the name or create a new issue.
> Fast copy for HDFS.
> -------------------
>
> Key: HDFS-2139
> URL: https://issues.apache.org/jira/browse/HDFS-2139
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Pritam Damania
> Attachments: HDFS-2139.patch
>
> Original Estimate: 168h
> Remaining Estimate: 168h
>
> There is a need to perform fast file copy on HDFS. The fast copy mechanism
> for a file works as
> follows :
> 1) Query metadata for all blocks of the source file.
> 2) For each block 'b' of the file, find out its datanode locations.
> 3) For each block of the file, add an empty block to the namesystem for
> the destination file.
> 4) For each location of the block, instruct the datanode to make a local
> copy of that block.
> 5) Once each datanode has copied over its respective blocks, they
> report to the namenode about it.
> 6) Wait for all blocks to be copied and exit.
> This would speed up the copying process considerably by removing top of
> the rack data transfers.
> Note : An extra improvement, would be to instruct the datanode to create a
> hardlink of the block file if we are copying a block on the same datanode
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