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https://issues.apache.org/jira/browse/HDFS-3425?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13397029#comment-13397029
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Todd Lipcon commented on HDFS-3425:
-----------------------------------
My plan is the following (similar to what you said:)
3. tail finalized segments
4. transit to active mode
5. calls recoverUnclosedStreams()
5a. Does the "recovery" process whereby it determines the correct txn to
synchronize to
5b. finalizes the last segment to this txnid on all the available JNs
6. reads the last finalized segment
7. begins writing at the next txid
I think this interface can be kept entirely generic --
recoverUnfinalizedSegments() is already a JM API which is implemented correctly
by FileJournalManager.
Looking at {{startActiveServices()}} we basically already take this approach of
calling {{recoverUnclosedStreams()}} followed by tailing edits one more time
before writing.
> Enable standby namenode to tail edits from journal service
> ----------------------------------------------------------
>
> Key: HDFS-3425
> URL: https://issues.apache.org/jira/browse/HDFS-3425
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha, name-node
> Reporter: Brandon Li
> Assignee: Brandon Li
> Attachments: HDFS-3425.HDFS-3092.patch, HDFS-3425.HDFS-3092.patch.2
>
>
> In an HA cluster with the journal service configured, namenode should get
> edit logs from journal service instead of from local or shared storage
> directories.
> As one of the first steps towards this goal, this JIRA is to enable standby
> namenode to tail edits from journal services.
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