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https://issues.apache.org/jira/browse/HDFS-5709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13873000#comment-13873000
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Aaron T. Myers commented on HDFS-5709:
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Patch looks pretty good to me. A few very small comments:
# I think this indentation is off:
{code}
+ // Rename .snapshot paths if we're doing an upgrade
+ parentPath = renameReservedPathsOnUpgrade(parentPath, getLayoutVersion(),
+ namesystem);
{code}
# I think we should consider scrapping the {{renameSnapshotPathChecked}}
variable. Seems like it's just for efficiency, but in practice this code should
only be triggered a relatively small number of times (since it only happens for
path components containing the reserved string) and I think we can reasonably
expect the JIT to take care of it, since it's really only checking conditions
that will never change for the lifetime of the process. You might also consider
moving the check that the replacement string doesn't contain the path separator
to NN startup time, since you can reasonably check the validity of that config
setting without there being any reserved names in the namespace.
# You might consider making FSNamesystem#renameSnapshotPath static so that you
don't have to pass a reference to the FSNamesystem into the FSImageFormat
methods.
# You should add some documentation about this setting to the snapshots docs.
> 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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