hadoop-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From bejoy.had...@gmail.com
Subject Re: Basic Doubt in Hadoop
Date Wed, 17 Apr 2013 05:00:49 GMT
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 <hadoopraj@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

Mime
View raw message