java.io.IOException: File /dfs_operator.txt could only be replicated to 0 nodes,

2011-07-28 16:47:24,312 INFO org.apache.hadoop.ipc.Server: IPC Server handler 7 on 9100, call addBlock(/dfs_operator.txt, DFSClient_344588298, null, null) from 192.168.2.15:36470: error: java.io.IOException: File /dfs_operator.txt could only be replicated to 0 nodes, instead of 1
java.io.IOException: File /dfs_operator.txt could only be replicated to 0 nodes, instead of 1
	at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1448)
	at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:690)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.hadoop.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:342)
	at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1350)
	at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1346)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:396)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:742)
	at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1344)

这个问题找了N久，最后发现是host的问题。

主要的错误信息（红色标记）：

STARTUP_MSG: Starting SecondaryNameNode
STARTUP_MSG:   host = RJ15/127.0.0.1





STARTUP_MSG:   args = []
STARTUP_MSG:   version = 0.21.0

将host配置，由

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1	RJ15





::1		localhost6.localdomain6 localhost6

192.168.2.15 master
192.168.2.82 slave1
192.168.2.102 slave2
192.168.2.69 slave3

 改成：

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1	master





::1		localhost6.localdomain6 localhost6

192.168.2.15 master
192.168.2.82 slave1
192.168.2.102 slave2
192.168.2.69 slave3

搞定。。。。

为什么要这么改，具体原因还不清楚，处于猜测状态，那位大牛来解释一下。谢谢。