= DFSAdmin 命令 = 

 * -report
報告HDFS的基本統計信息。有些信息也可以在NameNode Web服務首頁看到

{{{
$ bin/hadoop dfsadmin -report
}}}
   * 執行畫面
   {{{
Total raw bytes: 59529687040 (55.44 GB)
Remaining raw bytes: 46887116647 (43.67 GB)
Used raw bytes: 24576 (24 KB)
% used: 0%
Total effective bytes: 0 (0 KB)
Effective replication multiplier: Infinity
-------------------------------------------------
Datanodes available: 1
Name: 140.110.141.129:50010
State          : In Service
Total raw bytes: 59529687040 (55.44 GB)
Remaining raw bytes: 46887116647(43.67 GB)
Used raw bytes: 24576 (24 KB)
% used: 0%
Last contact: Wed Apr 01 14:49:39 CST 2009
   }}}

 * -safemode 
雖然通常並不需要，但是管理員的確可以手動讓NameNode進入或離開安全模式。

{{{
$ bin/hadoop dfsadmin -safemode

Usage: java DFSAdmin [-safemode enter | leave | get | wait]

}}}

{{{
$ bin/hadoop dfsadmin -safemode enter

Safe mode is ON


$ bin/hadoop dfsadmin -safemode leave

Safe mode is OFF
}}}

 不知道安全模式有何作用？？