【原創】hadoop啟動錯誤 找不到路由 解決方法

hadoop啟動過程中遇到下面的問題：


2012-07-04 18:43:20,763 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting DataNode
STARTUP_MSG:   host = slave1/192.168.18.87
STARTUP_MSG:   args = []
STARTUP_MSG:   version = 0.20.2
STARTUP_MSG:   build = https://svn.apache.org/repos/asf ... ranches/branch-0.20 -r 911707; compiled by 'chrisdo' on Fri Feb 19 08:07:34 UTC 2010
************************************************************/
2012-07-04 18:43:22,468 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 0 time(s).
2012-07-04 18:43:23,468 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 1 time(s).
2012-07-04 18:43:24,469 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 2 time(s).
2012-07-04 18:43:25,470 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 3 time(s).
2012-07-04 18:43:26,471 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 4 time(s).
2012-07-04 18:43:27,472 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 5 time(s).
2012-07-04 18:43:28,473 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 6 time(s).
2012-07-04 18:43:29,474 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 7 time(s).
2012-07-04 18:43:30,475 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 8 time(s).
2012-07-04 18:43:31,475 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.18.218:9000. Already tried 9 time(s).
2012-07-04 18:43:31,479 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: Call to /192.168.18.218:9000 failed on local exception: java.net.NoRouteToHostException: 沒有到主機的路由
        at org.apache.hadoop.ipc.Client.wrapException(Client.java:775)
        at org.apache.hadoop.ipc.Client.call(Client.java:743)
        at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:220)
        at $Proxy4.getProtocolVersion(Unknown Source)
        at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:359)
        at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:346)
        at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:383)
        at org.apache.hadoop.ipc.RPC.waitForProxy(RPC.java:314)
        at org.apache.hadoop.ipc.RPC.waitForProxy(RPC.java:291)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.startDataNode(DataNode.java:269)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.<init>(DataNode.java:216)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.makeInstance(DataNode.java:1283)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1238)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:1246)
        at org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:1368)
Caused by: java.net.NoRouteToHostException: 沒有到主機的路由
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:701)

NameNode啟動start-all.sh時出現上述錯誤，解決辦法如下：

(1)從namenode主機ping其它主機名（如：ping slave1），如果ping不通,原因可能是namenode節點的/etc/hosts配置錯誤

(2)從datanode主機ping namenode主機名，如果ping不通,原因可能是datenode節點的/etc/hosts配置的配置錯誤

解決辦法：以上兩種錯誤都需要修改/etc/hosts，同時保證集群中所有機器的/etc/hosts一致，參考：http://hi.baidu.com/tdfrank/blog/item/a1b9e1d95e3b013f10df9b01.html

(3)查看namenode主機的9000（具體根據core-site.xml中的fs.default.name節點配置）端口，是否打開，如果已打開(如下圖所示)，原因可能是防火牆開啟，解決辦法：關閉namenode和datanode主機的防火牆，或者設置防火牆開啟指定端口

[root@master swxing]# netstat -nap | grep 9000
tcp        0      0 ::ffff:192.168.18.218:9000  :::*                        LISTEN      4662/java           
tcp        0      0 ::ffff:192.168.18.218:46116 ::ffff:192.168.18.218:9000  ESTABLISHED 4859/java           
tcp        0      0 ::ffff:192.168.18.218:9000  ::ffff:192.168.18.87:36794  ESTABLISHED 4662/java           
tcp        0      0 ::ffff:192.168.18.218:9000  ::ffff:192.168.18.218:46116 ESTABLISHED 4662/java    　　

 

[root@master swxing]# service iptables stop

可以參考：http://www.cnblogs.com/siwei1988/archive/2012/07/12/2587527.html  設置開機不啟動防火牆服務，這樣就不用每次開機后都設置了。

(4)格式化硬盤（hadoop namenode -format）后啟動namenode(start-all.sh)

 

以上操作命令是在centos6.1中的操作命令，其它linux系統的操作命令可能有些不一樣，讀者根據自己的系統來定義操作，本文只提供一個思路。