The data is in HDFS in case of WordCount MR sample. In hdfs, you have the metadata in NameNode and actual data as blocks replicated across DataNodes.
In case of reducer, If a reducer is running on a particular node then you have one replica of the blocks in the same node (If there is no space issues) and rest replicas on other nodes. Regards Bejoy KS Sent from remote device, Please excuse typos -----Original Message----- From: Raj Hadoop <hadoop...@yahoo.com> Date: Tue, 16 Apr 2013 21:49:34 To: user@hadoop.apache.org<user@hadoop.apache.org> Reply-To: user@hadoop.apache.org Subject: Basic Doubt in Hadoop Hi, I am new to Hadoop. I started reading the standard Wordcount program. I got this basic doubt in Hadoop. After the Map - Reduce is done, where is the output generated? Does the reducer ouput sit on individual DataNodes ? Please advise. Thanks, Raj
