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MapReduce >> mail # user >> How to change topology


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Re: How to change topology
On 8 October 2012 14:23, Shinichi Yamashita <[EMAIL PROTECTED]> wrote:

> Hi,
>
> I know that DataNode and TaskTracker must restart to change topology.
>

no, it's the Namenode and JobTracker that needs to be restarted; they are
the bits that care where the boxes are.
> Is there the method to execute the topology change without restart of
> DataNode and TaskTracker?
> In other words, can I change the topology by a command?
>

No -the map gets cached, and when the services start up they do quick check
to see if the topology is flat or spread across switches -and use that flag
to make various placement decisions.

steve