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Posted to mapreduce-user@hadoop.apache.org by Ann Pal <an...@yahoo.com> on 2011/12/21 01:05:55 UTC

Application Master:

Hi,
I had the following questions related to Yarn:
[1] How does the Application Master know where the data is, to give a list to Resource Manager? Is it talking to the Name Node?
[2] How does Resource Manager interface with HDFS federation? How does it know which specific name node  talk to?

Thanks in advance!

Re: Application Master:

Posted by Arun C Murthy <ac...@hortonworks.com>.

On Dec 20, 2011, at 4:05 PM, Ann Pal wrote:

> Hi,
> I had the following questions related to Yarn:
> [1] How does the Application Master know where the data is, to give a list to Resource Manager? Is it talking to the Name Node?

Yes, it's the responsibility of the AM to talk to the NN to figure which hosts/racks it needs.

> [2] How does Resource Manager interface with HDFS federation? How does it know which specific name node  talk to?

Either full uri (hdfs://nn1:8080) or client-side mount tables.

Arun