本文介绍了“hadoop namenode -format”返回java.net.UnknownHostException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我目前正在学习hadoop，我正在尝试设置单一节点测试，如
我已配置ssh（我可以记录没有密码） 。
我的服务器在我们的内部网上，在代理后面。
当我试图运行
我得到以下java.net.UnknownHostException异常：
$ bin / hadoop namenode -format
11 / 10 15:36:47 INFO namenode.NameNode：STARTUP_MSG：
/ ******************************** ****************************
STARTUP_MSG：Starting NameNode
STARTUP_MSG：host = java.net.UnknownHostException： srv-clc-04.univ-nantes.prive3：srv-clc-04.univ-nantes.prive3
STARTUP_MSG：args = [-format]
STARTUP_MSG：version = 0.20.203.0
STARTUP_MSG：build = http://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-203 -r 1099333;由'oom'编译于5月4日星期三07:57:50 PDT 2011
****************************** ****************************** /
在/ home / lindenb / tmp / HADOOP / dfs中重新格式化文件系统/名称 ？ （Y或N）Y
11/06/10 15:36:50 INFO util.GSet：VM type = 64-bit
11/06/10 15:36:50 INFO util.GSet： 2％max memory = 19.1675 MB
11/06/10 15:36:50 INFO util.GSet：capacity = 2 ^ 21 = 2097152 entries
11/06/10 15:36:50 INFO util .GSet：recommended = 2097152，actual = 2097152
11/06/10 15:36:50 INFO namenode.FSNamesystem：fsOwner = lindenb
11/06/10 15:36:50 INFO namenode.FSNamesystem ：supergroup = supergroup
11/06/10 15:36:50 INFO namenode.FSNamesystem：isPermissionEnabled = true
11/06/10 15:36:50 INFO namenode.FSNamesystem：dfs.block.invalidate .limit = 100
11/06/10 15:36:50 INFO namenode.FSNamesystem：isAccessTokenEnabled = false accessKeyUpdateInterval = 0 min（s），accessTokenLifetime = 0 min（s）
11/06/10 15:36:50 INFO namenode.NameNode：缓存文件名发生超过10次
11/06/10 15:36:50 INFO common.Storage：大小为113的图像文件保存在0秒内。
11/06/10 15:36:50 INFO common.Storage：存储目录/ home / lindenb / tmp / HADOOP / dfs / name已成功格式化。
11/06/10 15:36:50 INFO namenode.NameNode：SHUTDOWN_MSG：
/ ************************ ************************************
SHUTDOWN_MSG：在java.net关闭NameNode。 UnknownHostException：srv-clc-04.univ-nantes.prive3：srv-clc-04.univ-nantes.prive3
******************* *************************************** /
之后，hadoop启动
。 /bin/start-all.sh
但有另一个新的异常，当我试图复制本地文件：
bin / hadoop fs -copyFromLocal〜/ file.txt file.txt
DataStreamer异常：org.apache.hadoop.ipc.RemoteException：java.io.IOException：File /user/lindenb/file.txt只能复制到0个节点，而不是org.apache.hadoop.hdfs中的1
。 server.namenode.FSNamesystem.getAdditionalBlock（FSNamesystem.java:1417）
如何解决这个问题？
感谢
解决方案在hadoop尝试解析DNS名称时被抛出（srv-clc -04.univ-nantes.prive3）到IP地址。
在配置文件中查找域名，并将其替换为localhost。 （或更新DNS解析名称为IP地址）
I'm currently learning hadoop and I'm trying to setup a single node test as defined in http://hadoop.apache.org/common/docs/current/single_node_setup.html
I've configured ssh (I can log without a password).
My server is on our intranet, behind a proxy.
When I'm trying to run
I get the following java.net.UnknownHostException exception:
$ bin/hadoop namenode -format 11/06/10 15:36:47 INFO namenode.NameNode: STARTUP_MSG: /************************************************************ STARTUP_MSG: Starting NameNode STARTUP_MSG: host = java.net.UnknownHostException: srv-clc-04.univ-nantes.prive3: srv-clc-04.univ-nantes.prive3 STARTUP_MSG: args = [-format] STARTUP_MSG: version = 0.20.203.0 STARTUP_MSG: build = http://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-203 -r 1099333; compiled by 'oom' on Wed May 4 07:57:50 PDT 2011 ************************************************************/ Re-format filesystem in /home/lindenb/tmp/HADOOP/dfs/name ? (Y or N) Y 11/06/10 15:36:50 INFO util.GSet: VM type = 64-bit 11/06/10 15:36:50 INFO util.GSet: 2% max memory = 19.1675 MB 11/06/10 15:36:50 INFO util.GSet: capacity = 2^21 = 2097152 entries 11/06/10 15:36:50 INFO util.GSet: recommended=2097152, actual=2097152 11/06/10 15:36:50 INFO namenode.FSNamesystem: fsOwner=lindenb 11/06/10 15:36:50 INFO namenode.FSNamesystem: supergroup=supergroup 11/06/10 15:36:50 INFO namenode.FSNamesystem: isPermissionEnabled=true 11/06/10 15:36:50 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100 11/06/10 15:36:50 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s) 11/06/10 15:36:50 INFO namenode.NameNode: Caching file names occuring more than 10 times 11/06/10 15:36:50 INFO common.Storage: Image file of size 113 saved in 0 seconds. 11/06/10 15:36:50 INFO common.Storage: Storage directory /home/lindenb/tmp/HADOOP/dfs/name has been successfully formatted. 11/06/10 15:36:50 INFO namenode.NameNode: SHUTDOWN_MSG: /************************************************************ SHUTDOWN_MSG: Shutting down NameNode at java.net.UnknownHostException: srv-clc-04.univ-nantes.prive3: srv-clc-04.univ-nantes.prive3 ************************************************************/After that, hadoop was started
./bin/start-all.shbut there was another new exception when I tried to copy a local file:
bin/hadoop fs -copyFromLocal ~/file.txt file.txt DataStreamer Exception: org.apache.hadoop.ipc.RemoteException: java.io.IOException: File /user/lindenb/file.txt could only be replicated to 0 nodes, instead of 1 at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1417)how can I fix this problem please ?
Thanks
解决方案UnknownHostException is thrown when hadoop tries to resolve the DNS name (srv-clc-04.univ-nantes.prive3) to an ip address. This fails.
Look for the domain name in the configuration files and replace it by "localhost". (Or update the DNS up resolve the name to an ip address)
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