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https://issues.apache.org/jira/browse/HDFS-5709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13881336#comment-13881336
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Andrew Wang commented on HDFS-5709:
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I'm not sure if this adds anything to the discussion, but the current workflow
in the patch is:
* By default, the config option is not set
* On upgrade, if we hit a .snapshot path, we throw an exception and abort
telling the user to set the config option
* When the config option is set, there are log prints whenever something is
renamed
This feels procedurally pretty similar to the alternative of a special startup
option, and it's only required to be set if we hit a .snapshot path. Most users
will never need to worry about this config.
I agree that doing renames with the context of the full parent path (e.g.
/X/.snapshot renames to /X/.myx-snapshot, /Y/.snapshot renames to
/Y/.myy.snapshot) would be more powerful, but IIUC that implies scanning the
fsimage and logs initially to enumerate all the .snapshot paths, have the user
configure their rename rules, then load the fsimage/logs again to do the rename.
Suresh, does any of this influence your view? I'd really like to move forward
on this issue.
> 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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