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https://issues.apache.org/jira/browse/HDFS-10314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15524359#comment-15524359
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Yongjun Zhang commented on HDFS-10314:
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Hi [~jingzhao],
To better address your comments, I discussed with [~atm], and we think there
are the following possible options:
Option 1. To get closer to what you suggested, we can introduce new tool
distsync and let it support all of the following semantics:
* distsync -diff s1 s2 src tgt
* distsync -rdiff s2 s1 src tgt
* distsync tgt s1
Implementation-wise, we can move common DistCp stuff to AbstractDistCp, and let
both DistCp and DistSync inherit from AbstractDistCp. Accordingly,
DistCpOption need to be refactored in a similar fashion.
With this route, the "-diff" in distcp will probably eventually be obsoleted.
Option 2. Given that we already have -diff switch in DistCp, we can add
"-rdiff" to DistCp, and support
* distcp -diff s1 s2 src tgt (currently supported)
* distcp -rdiff s2 s1 src tgt
Would you please share what you think?
Thanks a lot.
> A new tool to sync current HDFS view to specified snapshot
> ----------------------------------------------------------
>
> Key: HDFS-10314
> URL: https://issues.apache.org/jira/browse/HDFS-10314
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: tools
> Reporter: Yongjun Zhang
> Assignee: Yongjun Zhang
> Attachments: HDFS-10314.001.patch
>
>
> HDFS-9820 proposed adding -rdiff switch to distcp, as a reversed operation of
> -diff switch.
> Upon discussion with [~jingzhao], we will introduce a new tool that wraps
> around distcp to achieve the same purpose.
> I'm thinking about calling the new tool "rsync", similar to unix/linux
> command "rsync". The "r" here means remote.
> The syntax that simulate -rdiff behavior proposed in HDFS-9820 is
> {code}
> rsync <fromSnapshotName> <toSnapshotName> <source> <target>
> {code}
> This command ensure <fromSnapshotName> is newer than <toSnapshotName>.
> I think, In the future, we can add another command to have the functionality
> of -diff switch of distcp.
> {code}
> sync <fromSnapshotName> <toSnapshotName> <source> <target>
> {code}
> that ensures <fromSnapshotName> is older than <toSnapshotName>.
> Thanks [~jingzhao].
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