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https://issues.apache.org/jira/browse/HDFS-13079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16472323#comment-16472323
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Daryn Sharp commented on HDFS-13079:
------------------------------------
This appears to be a tricky to correctly wield "feature" (stop services, set
conf, start one, save namespace, stop services, remove conf, purge edits, start
service, re-bootstrap other, etc) that will be of little use to production ops.
By the time someone tells you their oopsy, the blocks are invalidated.
Does it make more sense to provide a dfsadmin command to effectively truncate
the edit logs and/or move newer images out of the way? Non-destructively of
course. Effectively achieves what you want but doesn't disturb normal code
paths.
> Provide a config to start namenode in safemode state upto a certain
> transaction id
> ----------------------------------------------------------------------------------
>
> Key: HDFS-13079
> URL: https://issues.apache.org/jira/browse/HDFS-13079
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Mukul Kumar Singh
> Assignee: Shashikant Banerjee
> Priority: Major
> Attachments: HDFS-13079.001.patch, HDFS-13079.002.patch,
> HDFS-13079.003.patch
>
>
> In some cases it necessary to rollback the Namenode back to a certain
> transaction id. This is especially needed when the user issues a {{rm -Rf
> -skipTrash}} by mistake.
> Rolling back to a transaction id helps in taking a peek at the filesystem at
> a particular instant. This jira proposes to provide a configuration variable
> using which the namenode can be started upto a certain transaction id. The
> filesystem will be in a readonly safemode which cannot be overridden
> manually. It will only be overridden by removing the config value from the
> config file. Please also note that this will not cause any changes in the
> filesystem state, the filesystem will be in safemode state and no changes to
> the filesystem state will be allowed.
> Please note that in case a checkpoint has already happened and the requested
> transaction id has been subsumed in an FSImage, then the namenode will be
> started with the next nearest transaction id. Further FSImage files and edits
> will be ignored.
> If the checkpoint hasn't happen then the namenode will be started with the
> exact transaction id.
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