Re: The location of the map execution

[Hassen Riahi]

Thanks for the suggestion!
The map is executed where the data is located when using the  
FairScheduler.

Hassen

Sorry, I meant have you set the mapred.jobtracker.taskScheduler
property in your mapred-site.xml file. If not, you're using the
standard, FIFO scheduler. The default scheduler doesn't do data-local
scheduling, but the fair scheduler and capacity scheduler do. You want
to set mapred.jobtracker.taskScheduler to either
org.apache.hadoop.mapred.FairScheduler (for the fair scheduler) or
org.apache.hadoop.mapred.CapacityTaskScheduler (for the capacity
scheduler) and then restart the JobTracker. You can read about the two
schedulers here:

http://hadoop.apache.org/common/docs/current/fair_scheduler.html
http://hadoop.apache.org/common/docs/current/capacity_scheduler.html

-Joey

On Sat, Mar 3, 2012 at 6:32 PM, Hassen Riahi <hassen.ri...@cern.ch>  
wrote:
The jobtracker is running in another machine (node C)

Hassen


Which scheduler are you using?

-Joey

On Mar 3, 2012, at 18:52, Hassen Riahi <hassen.ri...@cern.ch> wrote:

Hi all,

We tried using mapreduce to execute a simple map code which read  
a txt
file stored in HDFS and write then the output.
The file to read is a very small one. It was not split and written
entirely and only in a single datanode (node A). This node is  
configured
also as a tasktracker node
While we was expecting that the location of the map execution is  
node A
(since the input is stored there), from log files, we see that  
the map was
executed in another tasktracker (node B) of the cluster.
Am I missing something?

Thanks for the help!
Hassen





--
Joseph Echeverria
Cloudera, Inc.
443.305.9434