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From EdwardKing <zhan...@neusoft.com>
Subject Re: question about hadoop dfs
Date Sun, 26 Jan 2014 06:48:37 GMT
hdfs-site.xm is follows:
<configuration>
<property>
<name>dfs.name.dir</name>
<value>file:/home/software/name</value>
<description> </description>
</property>
<property>
<name>dfs.namenode.secondary.http-address</name>
<value>master:9001</value>
</property>
<property>
<name>dfs.data.dir</name>
<value>file:/home/software/data</value>
</property>
<property>
<name>dfs.http.address</name>
<value>master:9002</value>
</property>
<property>
<name>dfs.replication</name>
<value>2</value>
</property>
<property>
<name>dfs.datanode.du.reserved</name>
<value>1073741824</value>
</property>
<property>
<name>dfs.block.size</name>
<value>134217728</value>
</property>
<property>
<name>dfs.permissions</name>
<value>false</value>
</property>
</configuration>

[root@master ~]# cd /home
[root@master home]# cd software/
[root@master software]# ls
data   hadoop-2.2.0         jdk1.7.0_02                name  test.txt
file:  hadoop-2.2.0.tar.gz  jdk-7u2-linux-i586.tar.gz  temp  tmp

[root@master name]# pwd
/home/software/name
[root@master name]# ls
current  in_use.lock
[root@master name]# 

[root@master software]# pwd
/home/software
[root@master software]# cd data
[root@master data]# ls
current  in_use.lock

>> the meadata(file name, file path and block location) is in master, the file data
itself is in datanode.

Where I can find abc.txt meadata,such as file name, file path and block location?  The abc.txt
file data itself is in  master 172.11.12.6 or node1 172.11.12.7,which directory it locate?


Thanks.



----- Original Message ----- 
From: Jeff Zhang 
To: user@hadoop.apache.org 
Sent: Sunday, January 26, 2014 2:30 PM
Subject: Re: question about hadoop dfs


1. Is supergroup a directory?  Where does it locate?
    supergroup is user group rather than directory just like the user group of linux


2. I search abc.txt on master 172.11.12.6 and node1 172.11.12.7 by following command:
    the meadata(file name, file path and block location) is in master, the file data itself
is in datanode.





On Sun, Jan 26, 2014 at 2:22 PM, EdwardKing <zhangsc@neusoft.com> wrote:

I use Hadoop2.2.0 to create a master node and a sub node,like follows:

Live Datanodes : 2
Node  Transferring Address  Last Contact  Admin State  Configured Capacity (GB)  Used(GB)
 Non DFS Used (GB)  Remaining(GB)  Used(%)
master 172.11.12.6:50010         1                In Service           16.15             
                0.00              2.76                        13.39                 0.00
node1 172.11.12.7:50010         0                 In Service           16.15             
               0.00               2.75                        13.40                 0.00

Then I create a abc.txt file on master 172.11.12.6
[hadoop@master ~]$ pwd
/home/hadoop
[hadoop@master ~]$ echo "This is a test." >> abc.txt
[hadoop@master ~]$ hadoop dfs -copyFromLocal test.txt
[hadoop@master ~]$ hadoop dfs -ls
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

14/01/25 22:07:00 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your
platform... using builtin-java classes where applicable
Found 1 items
-rw-r--r--   2 hadoop supergroup         16 2014-01-25 21:36 abc.txt

[hadoop@master ~]$ rm abc.txt
[hadoop@master ~]$ hadoop dfs -cat abc.txt
This is a test.

My question is:
1. Is supergroup a directory?  Where does it locate?
2. I search abc.txt on master 172.11.12.6 and node1 172.11.12.7 by following command:
[hadoop@master ~]$ find / -name abc.txt
But I don't find abc.txt file. Where is the file abc.txt? After I erase it by rm command,
I still cat this file? Where is it? My OS is CentOS-5.8.

Thanks.
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