[
https://issues.apache.org/jira/browse/HDFS-2139?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17867636#comment-17867636
]
liuguanghua commented on HDFS-2139:
-----------------------------------
[~hexiaoqiao] , thanks for reply.
For 3 : fastcopy can use in a federation cluster, and in a single cluster ,
and in two different cluster with no federation. The difference is that
fastcopy will use hardlink in federation cluster or in a single cluster. And
fastcopy will use transfer in two different cluster with no federation.
Test Data:
blocksize 128M
1TB ECfiles + 1TB 3 replicated files
|distcp map=20|DIstcp via FastCopy(HardLink)|DistCp via
FastCopy(Transfer)|Distcp(original)|
|时间|5m6.687s|22m44.094s|38m17.024s|
[~zeekling] , fastcopy can improve data copy efficiency.
> 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
> Assignee: Rituraj
> Priority: Major
> Labels: pull-request-available
> Attachments: HDFS-2139-For-2.7.1.patch, HDFS-2139.patch,
> HDFS-2139.patch, image-2022-08-11-11-48-17-994.png
>
> 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
> [~xuzq_zander]Provided a design doc
> https://docs.google.com/document/d/1uGHA2dXLldlNoaYF-4c63baYjCuft_T88wdvhwVgh6c/edit?usp=sharing
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org
