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https://issues.apache.org/jira/browse/HDFS-10314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15528169#comment-15528169
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Yongjun Zhang commented on HDFS-10314:
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HI [~jingzhao],
I tried to provide details in my earlier replies so they tend to be lengthy.
Now I'd like to ask couple of quick questions on your latest proprosal (I asked
too in earlier reply but too buried). Appreciate your taking time to reply.
{quote}
In that sense, I think a simpler way is to wrap (but not extend) the current
distcp in the snapshot-restore tool:
1. The tool takes a single cluster and a target snapshot as arguments
2. The tool computes the delta for restoring using snapshot diff report
3. The tool does rename/delete etc. metadata ops to revert part of the diff
4. The tool uses the distcp (by invokes distcp as a library) to copy the
original states of modified files
{quote}
Q1: step 2 does the snapshot diff calculation as you described, does it also
collect the modified files and pass to step 4?
Q2: or does step 4 also do snapshot calculation?
Thanks much.
> 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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