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https://issues.apache.org/jira/browse/HDFS-1073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13064221#comment-13064221
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Jitendra Nath Pandey commented on HDFS-1073:
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A few comments:
1. EditLogFileInputStream doesn't have any change except for an unused import.
2. EditLogOutputStream.java : abstract void write(byte[] data, int i, int
length)
All transactions should have a txid, therefore this write method is
confusing. I guess it would be cleaned up with backup node fix. Please change
the parameter name 'i' to offset.
3. FSEditLog.java:
What is the reason to persist start and end of log segments? Do we really
need OP_START_LOG_SEGMENT and OP_END_LOG_SEGMENT?
4. FSEditLogOp.java
- LogHeader has a read method but not a write. Will it make sense to
encapsulate both read and write of the header in the same class?
5. NNStorage.java
- writeTransactionIdFileToStorage: The transaction id will be persisted
along with the image and log files. For a running namenode, it will be in the
in-memory state. It is not clear to me why do we need to persist a txid marker
separately.
6. There are unused imports in a few files.
7. I have a few concerns related to FSImageTransactionalStorageInspector,
FSEditLogLoader, but those parts have been addressed in HDFS-2018. I recommend
to commit HDFS-2018 in the branch as it significantly improves some parts of
the code.
> Simpler model for Namenode's fs Image and edit Logs
> ----------------------------------------------------
>
> Key: HDFS-1073
> URL: https://issues.apache.org/jira/browse/HDFS-1073
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Sanjay Radia
> Assignee: Todd Lipcon
> Attachments: hdfs-1073-editloading-algos.txt, hdfs-1073.txt,
> hdfs1073.pdf, hdfs1073.pdf, hdfs1073.pdf, hdfs1073.tex
>
>
> The naming and handling of NN's fsImage and edit logs can be significantly
> improved resulting simpler and more robust code.
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