今天，小乔操作时发现问题：
org.apache.hadoop.security.AccessControlException: Permission denied: user=root, access=WRITE, inode="/user":hdfs:supergroup:drwxr-xr-x
at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkFsPermission(FSPermissionChecker.java:265)
at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:251)
at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:232)
at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:176)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:5490)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:5472)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkAncestorAccess(FSNamesystem.java:5446)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInternal(FSNamesystem.java:3600)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInt(FSNamesystem.java:3570)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirs(FSNamesystem.java:3544)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.mkdirs(NameNodeRpcServer.java:739)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.mkdirs(ClientNamenodeProtocolServerSideTranslatorPB.java:558)
at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:585)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1026)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1986)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1982)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1980)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.apache.hadoop.ipc.RemoteException.instantiateException(RemoteException.java:106)
at org.apache.hadoop.ipc.RemoteException.unwrapRemoteException(RemoteException.java:73)
at org.apache.hadoop.hdfs.DFSClient.primitiveMkdir(DFSClient.java:2549)
at org.apache.hadoop.hdfs.DFSClient.mkdirs(DFSClient.java:2518)
at org.apache.hadoop.hdfs.DistributedFileSystem$16.doCall(DistributedFileSystem.java:827)
at org.apache.hadoop.hdfs.DistributedFileSystem$16.doCall(DistributedFileSystem.java:823)
at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirsInternal(DistributedFileSystem.java:823)
at org.apache.hadoop.hdfs.DistributedFileSystem.mkdirs(DistributedFileSystem.java:816)
at org.apache.hadoop.mapreduce.JobSubmissionFiles.getStagingDir(JobSubmissionFiles.java:125)
at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:348)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1295)
at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1292)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)
at org.apache.hadoop.mapreduce.Job.submit(Job.java:1292)
at org.apache.hadoop.mapred.JobClient$1.run(JobClient.java:562)
at org.apache.hadoop.mapred.JobClient$1.run(JobClient.java:557)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1548)
at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:557)
at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:548)
at org.apache.hadoop.hive.ql.exec.mr.ExecDriver.execute(ExecDriver.java:425)
at org.apache.hadoop.hive.ql.exec.mr.MapRedTask.execute(MapRedTask.java:136)
at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:151)
at org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:65)
at org.apache.hadoop.hive.ql.Driver.launchTask(Driver.java:1485)
at org.apache.hadoop.hive.ql.Driver.execute(Driver.java:1263)
at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1091)
at org.apache.hadoop.hive.ql.Driver.run(Driver.java:931)
at org.apache.hadoop.hive.ql.Driver.run(Driver.java:921)
at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:268)
at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:220)
at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:422)
at org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:790)
at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:684)
at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:623)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.hadoop.util.RunJar.main(RunJar.java:212)
解决办法网上有很多，差不多都是同样的，用修改配置的办法解决，，呵呵，我们用CDH实例时，WEB界面也可以解决的。。
conf/hdfs-core.xml, 找到 dfs.permissions 的配置项 , 将value值改为 false
<property>
<name>dfs.permissions</name>
<value>false</value>
<description>
If "true", enable permission checking in HDFS.
If "false", permission checking is turned off,
but all other behavior is unchanged.
Switching from one parameter value to the other does not change the mode,
owner or group of files or directories.
</description>
</property>
解决办法：
