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Posted to common-user@hadoop.apache.org by Saptarshi Guha <sa...@gmail.com> on 2008/05/20 18:03:48 UTC

Meaning of "Data-local map tasks" in the web status gui to MapReduce

Hello,
	Does the "Data-local map tasks" counter mean the number of tasks that  
the had the input data already present on the machine on they are  
running on? i.e the wasn't a need to ship the data to them.
	Thanks
	Saptarsh

Saptarshi Guha | saptarshi.guha@gmail.com | http://www.stat.purdue.edu/~sguha

Re: Meaning of "Data-local map tasks" in the web status gui to MapReduce

Posted by Arun C Murthy <ar...@yahoo-inc.com>.

On May 20, 2008, at 9:03 AM, Saptarshi Guha wrote:

> Hello,
> 	Does the "Data-local map tasks" counter mean the number of tasks  
> that the had the input data already present on the machine on they  
> are running on? i.e the wasn't a need to ship the data to them.

Yes.  Your understanding is correct.

More specifically it means that the map-task got scheduled on a  
machine on which one of the replicas of it's input-split-block was  
present and was served by the datanode running on that machine. *smile*

Arun