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From "Mahadev konar (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HDFS-1073) Simpler model for Namenode's fs Image and edit Logs
Date Wed, 14 Apr 2010 00:31:55 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12856706#action_12856706
] 

Mahadev konar commented on HDFS-1073:
-------------------------------------

I havent been able to read through all the comments, so pardon me if my comments do not make
much sense. Regarding using sequence numbers for naming edits and snapshots versus using transactions
ids, I would like to put forth a few reasons it has been really useful for us in ZooKeeper
to use transaction ids:

- checks for missing transactions. With file names as edits_txid and snashot_txid its very
easy to check if there was any missing transaction.
- debugging and finding the transaction you need is very easy. Lets say you want to dump the
transaction logs starting from transaction X. With the above scheme it becomes very easy to
search for the right transaction logs to start dumping from wherein no files need to be opened
to check what transactions they might have.

hopefully this helps.



> 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
>
> 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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