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Hadoop >> mail # user >> datanode replication


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Vishal Ghawate 2009-05-11, 06:20
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Re: datanode replication
Hey Vishal,

Check out the chooseTarget() method(s) of ReplicationTargetChooser.java in
the org.apache.hadoop.hdfs.server.namenode package:
http://svn.apache.org/viewvc/hadoop/core/trunk/src/hdfs/org/apache/hadoop/hdfs/server/namenode/ReplicationTargetChooser.java?view=markup
.

In words: assuming you're using the default replication level (3), the
default strategy will put one block on the local node, one on a node in a
remote rack, and another on that same remote rack.

Note that HADOOP-3799 (http://issues.apache.org/jira/browse/HADOOP-3799)
proposes making this strategy pluggable.

As for the example of a topology.script file, I'll let others handle that.

Regards,
Jeff

On Sun, May 10, 2009 at 11:20 PM, Vishal Ghawate <
[EMAIL PROTECTED]> wrote:

>
>
> hi,
> i just cant resolve how the namenode decide on where to place the replicas
> of the datanode
> can u also send me the example of the topology.script.file
> and how exactly it works
> thanks for referring my problem
>
> Vishal S. Ghawate
>
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Steve Loughran 2009-05-11, 10:12