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From gmac...@cs.ucf.edu
Subject Re: how to disperse the data uniformly?
Date Sat, 05 Jul 2008 19:13:37 GMT
for starters, you should probably change your replication value to 
something other than 1, it kinda defeats the purpose of a parallel 
distributed file system otherwise. What version of hadoop are you running? 
you should just be able to run the command

$bin/hadoop balancer 

to get the nodes balanced. However I don't remember what the tolerance 
value on the balancer is for the generic hadoop-default.xml file is. Since 
you only have 620MB on the cluster, then it might be within hadoop's range 
of okay data distribution. Run the balancer first and see what happens\

 - Grant

On Jul 4 2008, Yi Zhao wrote:

>I have two datanode as below:
>one namenode below:
>when I put a file 600M and a file 20M into dfs, I found that all data is
>centralized in one datanode!!
>how to disperse all the data to all datanode uniformly?
>my hadoop-site.xml is:
><?xml version="1.0"?>
><?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
><!-- Put site-specific property overrides in this file. -->
>	<property>
>		<name>fs.default.name</name>
>		<value></value>
>		<description>the name of the default file system, either the literal
>string "local" or a host:port for DFS.</description>
>	</property>
>	<property>
>		<name>mapred.job.tracker</name>
>		<value></value>
>		<description>the host and port that MapReduce job tracker runs at. if
>"local", then jobs are run in-process as a single map and reduce
>	</property>
>	<property>
>		<name>hadoop.tmp.dir</name>
>		<value>/home/kongming/devel/hadoop/tmp</value>
>		<description>a base for other temporary directories.</description>
>	</property>
>	<property>
>		<name>dfs.name.dir</name>
>		<value>/home/kongming/devel/hadoop/fs/name</value>
>		<description>determines where on the local filesystem the DFS name
>node should store the name table. if this is a comma-delimited list of
>directories then the name table is replicated in all of the directories,
>for redundancy.</description>
>	</property>
>	<property>
>		<name>dfs.data.dir</name>
>		<value>/home/kongming/devel/hadoop/fs/data</value>
>		<description>determines where on the local filesystem on DFS data node
>should store its blocks. if this is a comma-delimited list of
>directories, then data will be stored in all named directories,
>typically on different devices. derectories that do not exist are
>	</property>
>	<property>
>		<name>dfs.replication</name>
>		<value>1</value>
>		<description>default block replication. the actual number of
>replications can be specified when the file is created. the default is
>used if replication is not specified in create time</description>
>	</property>

Grant Mackey
UCF Researcher
Eng. III Rm238

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