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From "dhruba borthakur (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-227) Namespace check pointing is not performed until the namenode restarts.
Date Fri, 15 Dec 2006 05:42:24 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-227?page=comments#action_12458679 ] 
            
dhruba borthakur commented on HADOOP-227:
-----------------------------------------

I agree that we can introduce a new Protocol called the SecondaryNamenodeProcotol. 

I would still persist with the proposal that the primary namenode is just a "slave" as far
as periodic checkpointing is concerned. All the "intelligence" of when to create the checkpoint,
how to create it, etc.etc remains with the SecondaryNamenode. In the case when we support
multiple Secondary namenodes doing their own periodic checkpointing according to their own
schedules, the primary Namenode would otherwise have to do lots of schedule management for
each of these periodic-checkpointers.



> Namespace check pointing is not performed until the namenode restarts.
> ----------------------------------------------------------------------
>
>                 Key: HADOOP-227
>                 URL: http://issues.apache.org/jira/browse/HADOOP-227
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.2.0
>            Reporter: Konstantin Shvachko
>         Assigned To: dhruba borthakur
>         Attachments: patch-async-checkpoints-0.9.0, patch-async-checkpoints-0.9.0, patch-async-checkpoints-0.9.0
>
>
> In current implementation when the name node starts, it reads its image file, then
> the edits file, and then saves the updated image back into the image file.
> The image file is never updated after that.
> In order to provide the system reliability reliability the namespace information should
> be check pointed periodically, and the edits file should be kept relatively small.

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