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https://issues.apache.org/jira/browse/HDFS-5920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13896828#comment-13896828
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Jing Zhao commented on HDFS-5920:
---------------------------------
HDFS-5753 already defines the Rollback option for rolling upgrade. Users can
use "-rollingUpgrade rollback" to start the NameNode and rollback the NameNode
to the status before starting the rolling upgrade.
Since NN will do a checkpoint right before the upgrade marker, for rollback, we
only need to go back to that fsimage, and delete all the editlog segments on or
above (marker txid - 1). This editlog deletion should happen in both NN's local
directory and shared storage (JNs for QJM's HA setup).
> Support rollback of rolling upgrade in NameNode and JournalNodes
> ----------------------------------------------------------------
>
> Key: HDFS-5920
> URL: https://issues.apache.org/jira/browse/HDFS-5920
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: journal-node, namenode
> Reporter: Jing Zhao
> Assignee: Jing Zhao
>
> This jira provides rollback functionality for NameNode and JournalNode in
> rolling upgrade.
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