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https://issues.apache.org/jira/browse/HDFS-5709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13884987#comment-13884987
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Andrew Wang commented on HDFS-5709:
-----------------------------------
I had a quick call with Suresh to hash this out, and we arrived at the
following which should be suitable for everyone:
* Rather than a configuration option which can stick around forever, an
additional command line flag (e.g. "-upgrade -renameReserved") is better. This
way we worry about it once, and there are no lingering effects.
* We default to renaming reserved paths to a convention like
{{.snapshot.LV.UPGRADE_RENAMED}}, but also allow users to pass key/value pairs
on the command line, e.g. "-upgrade -renameReserved .snapshot=.user-snapshot".
In either case, we should do our best to detect collisions, but it's hard with
the edit log.
* It'd be good to do this for "/.reserved" too, which will help demonstrate
that this is a generic solution.
I think this is an accurate summary, so I'll start revving the patch as per
above. Please comment if something is still off.
> Improve upgrade with existing files and directories named ".snapshot"
> ---------------------------------------------------------------------
>
> Key: HDFS-5709
> URL: https://issues.apache.org/jira/browse/HDFS-5709
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 3.0.0, 2.2.0
> Reporter: Andrew Wang
> Assignee: Andrew Wang
> Labels: snapshots, upgrade
> Attachments: hdfs-5709-1.patch, hdfs-5709-2.patch, hdfs-5709-3.patch,
> hdfs-5709-4.patch, hdfs-5709-5.patch
>
>
> Right now in trunk, upgrade fails messily if the old fsimage or edits refer
> to a directory named ".snapshot". We should at least print a better error
> message (which I believe was the original intention in HDFS-4666), and [~atm]
> proposed automatically renaming these files and directories.
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