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https://issues.apache.org/jira/browse/HDFS-3797?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Todd Lipcon resolved HDFS-3797.
-------------------------------
Resolution: Fixed
Fix Version/s: QuorumJournalManager (HDFS-3077)
Hadoop Flags: Reviewed
> QJM: add segment txid as a parameter to journal() RPC
> -----------------------------------------------------
>
> Key: HDFS-3797
> URL: https://issues.apache.org/jira/browse/HDFS-3797
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha
> Affects Versions: QuorumJournalManager (HDFS-3077)
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Minor
> Fix For: QuorumJournalManager (HDFS-3077)
>
> Attachments: hdfs-3797.txt
>
>
> During fault testing of QJM, I saw the following issue:
> 1) NN sends txn 5 to JN
> 2) NN gets partitioned from JN while JN remains up. The next two RPCs are
> missed while the partition has happened:
> 2a) finalizeSegment(1-5)
> 2b) startSegment(6)
> 3) NN sends txn 6 to JN
> This caused one of the JNs to end up with a segment 1-10 while the others had
> two segments; 1-5 and 6-10. This broke some invariants of the QJM protocol
> and prevented the recovery protocol from running properly.
> This can be addressed on the client side by HDFS-3726, which would cause the
> NN to not send the RPC in #3. But it makes sense to also add an extra safety
> check here on the server side: with every journal() call, we can send the
> segment's txid. Then if the JN and the client get "out of sync", the JN can
> reject the RPCs.
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