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https://issues.apache.org/jira/browse/HDFS-5709?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13882103#comment-13882103
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Suresh Srinivas commented on HDFS-5709:
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bq. 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.
The problem is, now we have a configuration that needs to be added to NameNode
for one time upgrade. The configuration lingers on for ever, unless and
informed user can get rid of it. That is the reason why configuration is
perhaps not the best way to do this.
The mechanism I and [~jingzhao] talked about addresses .reserved as well. Do
you plan to address that in this jira?
bq. ...that implies scanning the fsimage and logs initially to enumerate all
the .snapshot paths, have the user configure their rename rules...
Or, just rename it based on convention as I had proposed. User can either glean
this from the log (preferred) or from searching fsimage the renamed paths and
rename them as they wish. Given that the likelihood of users running into this
conflict in the first place is low, this should be acceptable.
> 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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