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https://issues.apache.org/jira/browse/HDFS-5709?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrew Wang updated HDFS-5709:
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Attachment: hdfs-5709-1.patch
Binary patch attached. High-level notes:
* I went with a full-substitution for reserved path components with the new
configuration option, with the understanding that ".user-snapshot" is a
prettier format. By default, this is null and will make the user set it if we
encounter a .snapshot path during upgrade.
* Should be easy to extend if we ever have add more reserved paths. I went
through and munged all the edit log ops except the cache directive ones; I
think these are okay to skip since they won't prevent the NN from starting up,
but I can do them too if desired.
* It's hard to check that the destination of the rename is safe, so I don't.
The issue is if we rename something to {{.user-snapshot}} and the edit log
later touchz's or mkdirs {{.user-snapshot}}. We could check for
{{.user-snapshot}} in all paths flying by, but then we'd be precluding that
from being used anywhere in the namespace, not just where it might collide in
later edit log ops.
* New test and provided tarball have an image and edits that refer to
".snapshot" paths. I did a variety of touch and mkdir operations.
> 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
>
>
> 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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