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From "Konstantin Shvachko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-227) Namespace check pointing is not performed until the namenode restarts.
Date Fri, 15 Dec 2006 19:49:24 GMT
    [ http://issues.apache.org/jira/browse/HADOOP-227?page=comments#action_12458905 ] 
            
Konstantin Shvachko commented on HADOOP-227:
--------------------------------------------

My idea of supporting multiple secondary nodes was that the primary node always deals with
ONE secondary node, which in turn
becomes the "primary" node for next secondary node, and so on. The order of the nodes is defined
by how the secondary nodes
are listed in the config file. That way each name-node need to know and speak to only one
secondary, which substantially
simplifies the logic. The primary decides when the new check point should be created and initiates
the chain of checkpoints.
I think we want to avoid heartbeat processing from secondary nodes and minimize inter-name-node
communication traffic.

I'd prefer to have all configuration in config file rather than configurable paths to other
files, containing edditional configuration parameters.
Don't like the last proposal linking "masters" in the config. This will make configration
even more complicated.

> 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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