安装hadoop错误一则：/tmp/hadoop-grid/mapred/system/jobtracker.info could only be replicated to 0 nodes...
现象：
--节点进程显示都是正常的呀
[grid@gc logs]$ /usr/java/jdk1.6.0_18/bin/jps
4434 JobTracker
4346 SecondaryNameNode
4194 NameNode
8291 Jps
[grid@rac1 conf]$ /usr/java/jdk1.6.0_18/bin/jps
32423 Jps
29224 DataNode
29348 TaskTracker
[grid@rac2 logs]$ /usr/java/jdk1.6.0_18/bin/jps
26358 DataNode
26457 TaskTracker
1210 Jps
--master节点的jobtracker日志
[grid@gc logs]$ tail -100f hadoop-grid-jobtracker-gc.localdomain.log
2012-11-23 15:49:26,973 WARN org.apache.hadoop.hdfs.DFSClient: Error Recovery for block null bad datanode[0] nodes == null
2012-11-23 15:49:26,973 WARN org.apache.hadoop.hdfs.DFSClient: Could not get block locations. Source file "/tmp/hadoop-grid/mapred/system/jobtracker.info" - Aborting...
2012-11-23 15:49:26,974 WARN org.apache.hadoop.mapred.JobTracker: Writing to file hdfs://gc.localdomain:9000/tmp/hadoop-grid/mapred/system/jobtracker.info failed!
2012-11-23 15:49:26,975 WARN org.apache.hadoop.mapred.JobTracker: FileSystem is not ready yet!
2012-11-23 15:49:26,977 WARN org.apache.hadoop.mapred.JobTracker: Failed to initialize recovery manager.
org.apache.hadoop.ipc.RemoteException: java.io.IOException: File /tmp/hadoop-grid/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1271)
at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:422)
at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:508)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:959)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:955)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:953)
at org.apache.hadoop.ipc.Client.call(Client.java:740)
at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:220)
at $Proxy4.addBlock(Unknown Source)
at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:82)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:59)
at $Proxy4.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.locateFollowingBlock(DFSClient.java:2937)
at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStream(DFSClient.java:2819)
at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2000(DFSClient.java:2102)
at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:2288)
--slave 1节点日志
[grid@rac1 logs]$ more hadoop-grid-datanode-rac1.localdomain.log
2012-11-23 15:33:28,815 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.101:9000. Already tried 7 time(s).
2012-11-23 15:33:29,817 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.101:9000. Already tried 8 time(s).
2012-11-23 15:33:30,818 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.101:9000. Already tried 9 time(s).
2012-11-23 15:33:30,819 INFO org.apache.hadoop.ipc.RPC: Server at /192.168.2.101:9000 not available yet, Zzzzz...
2012-11-23 15:33:32,820 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.101:9000. Already tried 0 time(s).
2012-11-23 15:33:33,821 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.101:9000. Already tried 1 time(s).
--slave 2节点日志
[grid@rac2 logs]$ more hadoop-grid-datanode-rac2.localdomain.log
2012-11-23 15:34:19,661 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 9 time(s).
2012-11-23 15:34:19,663 INFO org.apache.hadoop.ipc.RPC: Server at /192.168.2.102:9001 not available yet, Zzzzz...
2012-11-23 15:34:21,665 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 0 time(s).
2012-11-23 15:34:22,666 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 1 time(s).
2012-11-23 15:34:23,667 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 2 time(s).
2012-11-23 15:34:24,674 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 3 time(s).
2012-11-23 15:34:25,683 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 4 time(s).
2012-11-23 15:34:26,685 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 5 time(s).
2012-11-23 15:34:27,690 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 6 time(s).
2012-11-23 15:34:28,703 INFO org.apache.hadoop.ipc.Client: Retrying connect to server: /192.168.2.102:9001. Already tried 7 time(s).
jobtracker监控界面：
namenode集群监控界面：
原因：
是因为两个slave节点的core-site.xml和mapred-site.xml文件配置的问题
之前对安装说明解决有误，一直以为在ore-site.xml和mapred-site.xml配置文件中IP或机器名应为各自机器的IP或机器名。
所以我之前把两个slave节点的core-site.xml和mapred-site.xml文件配置成了自己机器的IP。
应该都改成master机器的IP或机器名，如下：
--1 master 及 2 slave nodes 的 core-site.xml 和 mapred-site.xml 配置
[grid@gc conf]$ cat core-site.xml
[grid@gc conf]$ cat mapred-site.xml
然后重启hadoop正常
问题帖子：http://f.dataguru.cn/thread-32858-1-1.html
总结：
在安装配置hadoop时，如果出现问题，可以主要按下面的步骤检查：
1、节点的映射，master，slave1；slave2。。。；2、ssh互信，master—》slave1；master—》slave2；
3、各个服务器上的hadoop的配置文件确认正确，安装目录一致，tmp，data目录也要一致；
4、防火墙要关闭：/etc/init.d/iptables stop