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https://issues.apache.org/jira/browse/HDFS-6038?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13921881#comment-13921881
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Tsz Wo Nicholas Sze commented on HDFS-6038:
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- It may be easier to implement DataOutputBuffer.writeInt(..) if we add
Buffer.setCount(..), i.e. get old count, set new count, writeInt and then
update count.
- FSEditLogOp.scanOp(), it should use in.skip(..) instead of readFully(..).
- EditLogInputStream.scanNextOp() could have a default implementation -- it
just call readOp and return txid or throw UnsupportedOperationException. Only
EditLogFileInputStream override it and the other subclasses don't.
> JournalNode hardcodes NameNodeLayoutVersion in the edit log file
> ----------------------------------------------------------------
>
> Key: HDFS-6038
> URL: https://issues.apache.org/jira/browse/HDFS-6038
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, ha, hdfs-client, namenode
> Reporter: Haohui Mai
> Assignee: Jing Zhao
> Attachments: HDFS-6038.000.patch, HDFS-6038.001.patch,
> HDFS-6038.002.patch, HDFS-6038.003.patch, editsStored
>
>
> In HA setup, the JNs receive edit logs (blob) from the NN and write into edit
> log files. In order to write well-formed edit log files, the JNs prepend a
> header for each edit log file.
> The problem is that the JN hard-codes the version (i.e.,
> {{NameNodeLayoutVersion}} in the edit log, therefore it generates incorrect
> edit logs when the newer release bumps the {{NameNodeLayoutVersion}} during
> rolling upgrade.
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