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From oj...@doc.ic.ac.uk
Subject Re: Running tasktrackers on datanodes
Date Tue, 31 Jul 2007 13:50:09 GMT
Hi Lucas,

Sounds strange, it should work. As long as you have all the names of  
the slave machines in the slaves file the start-mapred script should  
ssh into each one and start a tasktracker. Immediate thoughts are: Is  
your ssh working? Is hadoop installed on the same directory structure  
as on the machine you run the script from (ignore if running from NFS  
mount). Have you looked in the error logs on the slave machines, there  
might be some useful information there if the script tried to start a  
tasktracker and failed? What does the console print when you run  
hadoop-mapred.sh? It should say something like "machinex: starting  
tasktracker, logging to /somefile/" for each machine listed in your  
slaves file.

Good luck,

Quoting Lucas Nazário dos Santos <nazario.lucas@gmail.com>:

> Hello,
> I was reading Hadoop's getting started (
> http://wiki.apache.org/lucene-hadoop/GettingStartedWithHadoop), and in the
> section named "Starting up a larger cluster" I had a doubt about starting
> tasktrackers on datanodes. The tutorial says that after running the
> start-dfs.sh script on the node I want as the namenode, I need to execute
> the script start-mapred.sh, and this will "bring up the Map/Reduce cluster
> with Jobtracker running on the machine you ran the command on and
> Tasktrackers running on machines listed in the slaves file".
> It actually brings up the Jobtracker on the machine I ran the command on,
> but not the tasktrackers on slave machines. I need to enter slave by slave
> starting the tasktracker manually, issuing the command "hadoop tasktracker"
> what, according to Hadoop's getting started documentation, is something
> unnecessary.
> Did I misunderstand something?
> Thanks in advance,
> Lucas

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