异常1：2011-08-03 17:52:26,244 INFO org.apache.hadoop.ipc.Server: IPC Server handler 6 on 9800, call getListing(/home/fish/tmp20/mapred/system) from 192.168.2.101:2936: error: org.apache.hadoop.security.AccessControlException: Permission denied: user=DrWho, access=READ_EXECUTE, inode="system":root:supergroup:rwx-wx-wx
org.apache.hadoop.security.AccessControlException: Permission denied: user=DrWho, access=READ_EXECUTE, inode="system":root:supergroup:rwx-wx-wx
at org.apache.hadoop.hdfs.server.namenode.PermissionChecker.check(PermissionChecker.java:176)
at org.apache.hadoop.hdfs.server.namenode.PermissionChecker.checkPermission(PermissionChecker.java:111)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4514)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPathAccess(FSNamesystem.java:4474)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getListing(FSNamesystem.java:1989)
at org.apache.hadoop.hdfs.server.namenode.NameNode.getListing(NameNode.java:556)
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.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)
解决方法：在hdfs-site.xml里加入下面的
<property>
<name>dfs.permissions</name>
<value>false</value>
</property>
异常2： 2011-09-11 10:59:38,203 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: java.io.IOException: Incompatible namespaceIDs in E:\tmp\hadoop-SYSTEM\dfs\data: namenode namespaceID = 656078280; datanode namespaceID = 942585988
at org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:233)
at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:148)
at org.apache.hadoop.hdfs.server.datanode.DataNode.startDataNode(DataNode.java:298)
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)
解决方法：http://blog.csdn.net/wh62592855/article/details/5752199
异常3：Exception in thread "main" java.io.IOException: Cannot run program
"chmod": CreateProcess error=2, The system cannot find the file
specified
原因：是执行不了unix的命令。解决方法是把cygwin/bin路径添加到path下面去
步骤：
* Control Panel -> System and Security -> System ->
Advanced System Settings
* Click on the "Advanced" tab
* Click "Environment Variables" button
* Select "Path", click "Edit"
* Add ";C:\cygwin\bin" to the end of the "variable value"
异常4：
PC之间时间不同步（hbase）
FATAL org.apache.hadoop.hbase.regionserver.HRegionServer: Master rejected startup because clock is out of sync org.apache.hadoop.hbase.ClockOutOfSyncException: org.apache.hadoop.hbase.ClockOutOfSyncException: Server suc-pc,60020,1363269953286 has been rejected; Reported time is too far out of sync with master. Time difference of 39375ms > max allowed of 30000ms
小问题，一看就知道错误发生在哪。在hbase中，允许小的时间偏差，但是上面39秒的时间偏差就有点大了。如果你是联网的话，可以用ntpdate 219.158.14.130进行同步。219.158.14.130是网通北京的时间服务器，如果不行你可以用别的服务器进行同步。
2、zookeeper服务器未设置或者/etc/hosts设置有误（hbase）
2013-03-11 19:41:08,263 INFO org.apache.zookeeper.ClientCnxn: Opening socket connection to server localhost/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) 2013-03-11 19:41:08,266 WARN org.apache.zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect java.net.ConnectException: 拒绝连接 at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method) at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:692) at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:350) at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1068)
这个问题的出现，会伴随一个非常奇怪的现象。在master所在的pc上启动start-all时，内容提示所有的regionserver已经全部启动。但是，如果你去查看masterIP：60010时会发现其他的regionserver并没有启动，regionserver的数量只有一台。因为已经有一台regionserver是活着的，所以hbase还是能继续使用的，这会迷惑你。查看别的机器的日志后，你就会发现上述错误。zookeeper的定位居然定位到127.0.0.1去了，这个不科学。最后，查阅资料才发现hbase.zookeeper.quorum这个属性设置时，默认本机即为zookeeper服务器（单机使用）。这就很简单了，只需要增加这个属性就可以了。
<property> <name>hbase.zookeeper.quorum</name> <value>10.82.58.213</value> </property>
同时，也发现如果/etc/hosts设置错误也会发生类似问题。/etc/hosts中，localhost和本机PC名都需要为127.0.0.1，因为本机PC名默认是127.0.1.1。
参考：http://mail-archives.apache.org/mod_mbox/hbase-user/201106.mbox/%[email protected]%3E