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From Allen Wittenauer <awittena...@linkedin.com>
Subject Re: rack awareness help
Date Thu, 04 Mar 2010 05:21:21 GMT
On 3/3/10 5:01 PM, "Mag Gam" <magawake@gmail.com> wrote:

> Thanks Alan! Your presentation is very nice!

Thanks. :)

> "If you don't provide a script for rack awareness, it treats every
> node as if it was its own rack". I am using the default settings and
> the report still says only 1 rack.

Let's take a different approach to convince you. :)

Think about the question:  Is there a difference between all nodes in one
rack vs. every node acting as a lone rack?

The answer is no, there isn't any difference.  In both cases, all copies of
the blocks can go to pretty much any node. When a MR job runs, every node
would either be considered 'off rack' or 'rack-local'.

So there is no difference.


> Do you mind sharing a script with us on how you determine a rack? and
> a sample <configuration> </configuration> syntax?

Michael has already posted his, so I'll skip this one. :)


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