Pedro, Job tracker is there just to invoke the job or submit the job. It doesn't play any role in split and map. Here in your question mapper play a role to get splits.
Thanks Sent from my BlackBerry, pls excuse typo -----Original Message----- From: Pedro Costa <psdc1...@gmail.com> Date: Wed, 7 Mar 2012 13:57:28 To: mapreduce-user<mapreduce-user@hadoop.apache.org> Reply-To: mapreduce-user@hadoop.apache.org Subject: Split locations Hi, In MapReduce, if the locations of the split are in {HostA, HostB, HostC}, and the respective map tasks will run in HostB, the map tasks will pick up the split from HostB? Who is responsible to make the map tasks get the spilt in HostB? Is the JobTracker or the MapTask? -- Best regards,