Ubuntu 12.10 安装JDK、Hadoop全过程(2)

7、测试可否使用ssh登陆localhost（执行后屏幕的提示忘了copy，如有提示，输入yes）：
Now check that you can ssh to the localhost without a passphrase:
$ ssh localhost
如果无法登录，则主动生成key：
If you cannot ssh to localhost without a passphrase, execute the following commands:
$ ssh-keygen -t dsa -P '' -f ~/.ssh/id_dsa
屏幕提示（部分数据已用*代替）：
Generating public/private dsa key pair.
Your identification has been saved in /home/Hadoop/.ssh/id_dsa.
Your public key has been saved in /home/hadoop/.ssh/id_dsa.pub.
The key fingerprint is:
b3:5d:c4:*** hadoop@Baron-SR25E
The key's randomart image is:
+--[ DSA 1024]----+
| ...o E... |
| . ...= .. |
| o .. + |
| . * |
| S + o |
| = = . |
| . o o o |
| . o . |
| ... . |
+-----------------+
免输入密码登陆ssh：
$ cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
将ssh密钥追加到authorized_keys后面，即可实现免密钥登陆。
8、执行格式化namenode：
Format a new distributed-filesystem:
$ bin/hadoop namenode -format
12/11/10 16:25:48 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = Baron-SR25E/127.0.1.1
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = 1.0.4
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0 -r 1393290; compiled by 'hortonfo' on Wed Oct 3 05:13:58 UTC 2012
************************************************************/
12/11/10 16:25:49 INFO util.GSet: VM type = 32-bit
12/11/10 16:25:49 INFO util.GSet: 2% max memory = 17.77875 MB
12/11/10 16:25:49 INFO util.GSet: capacity = 2^22 = 4194304 entries
12/11/10 16:25:49 INFO util.GSet: recommended=4194304, actual=4194304
12/11/10 16:25:49 INFO namenode.FSNamesystem: fsOwner=root
12/11/10 16:25:49 INFO namenode.FSNamesystem: supergroup=supergroup
12/11/10 16:25:49 INFO namenode.FSNamesystem: isPermissionEnabled=true
12/11/10 16:25:49 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100
12/11/10 16:25:49 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
12/11/10 16:25:49 INFO namenode.NameNode: Caching file names occuring more than 10 times
12/11/10 16:25:50 INFO common.Storage: Image file of size 110 saved in 0 seconds.
12/11/10 16:25:50 INFO common.Storage: Storage directory /tmp/hadoop-root/dfs/name has been successfully formatted.
12/11/10 16:25:50 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at Baron-SR25E/127.0.1.1
************************************************************/