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https://issues.apache.org/jira/browse/HDFS-4523?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13586246#comment-13586246
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Aaron T. Myers commented on HDFS-4523:
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Hi Nicholas, unless I'm misunderstanding something, I think I question the
premise of this JIRA. Judging by the description, it sounds like you're saying
that when a concat(...) is performed on a set of files after those files have
been included in a snapshot, that that snapshot should be modified to include
the final concat'ed file, instead of the constituent files pre-concat. That
would seem to violate the "read-only" premise of snapshots, which doesn't seem
like the correct behavior to me.
Please let me know if I misunderstood the intent of this JIRA.
Thanks.
> Fix concat for snapshots
> ------------------------
>
> Key: HDFS-4523
> URL: https://issues.apache.org/jira/browse/HDFS-4523
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
> Attachments: h4523_20130222.patch, h4523_20130223.patch
>
>
> The use case of concat is for copying large files across clusters using the
> following steps.
> - Step 1: The blocks of a file in the source cluster are copied in parallel
> to transient files in the destination cluster.
> - Step 2: Then the transient files in the destination cluster are
> concatenated in order to obtain the original file.
> If a snapshot is taken in the destination cluster before Step 2, some
> transient files may be captured in the snapshot. These transient files
> should be removed in Step 2.
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