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https://issues.apache.org/jira/browse/HDFS-16792?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mukund Thakur updated HDFS-16792:
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Target Version/s: 3.3.9 (was: 3.4.0, 3.3.5)
> Add -newEditsOnly option to name node initializeSharedEdits command to format
> unformatted journal nodes for master replacement
> ------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-16792
> URL: https://issues.apache.org/jira/browse/HDFS-16792
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: journal-node
> Affects Versions: 3.3.3, 3.3.4
> Reporter: Ashutosh Gupta
> Assignee: Ashutosh Gupta
> Priority: Major
> Labels: pull-request-available
>
> Add -newEditsOnly option to name node initializeSharedEdits command to format
> unformatted journal nodes for master replacement.
>
> The current hadoop has limitations on formatting journal nodes. First, it
> requires all journal nodes to be present when formatting name node. After
> that, new journal nodes could not be formatted unless we reformat all of them
> and destroy all HDFS edit logs.
>
> $ hdfs namenode -initializeSharedEdits -newEditsOnly
> There are two cases here:
> 1) the replaced master instance has name node running on it, then the above
> command will only be run once on the existing name node.
> 2) the replaced master instance does not have a name node running on it, then
> the above command will be run twice. But the above command is idempotent as
> long as the same command will not be issued at the same time, which could be
> guaranteed by instance controller when reconfiguring master instances. The
> reason is that all hadoop name node commands such as format, bootstrap, and
> initializeSharedEdits are not designed to be thread safe and they rely on an
> external mechanism, which is a manual work for hadoop admin for on-premise
> clusters, to make sure that they are not executed concurrently. We still keep
> the same behavior of the initializeSharedEdits command to minimize the
> code/logic changes.
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