hbase启动时，查看log日志，报错如下：
2015-05-05 14:58:32,926 FATAL [master:16020.activeMasterManager] master.HMaster: Failed to become active master
org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.AccessControlException): SIMPLE authentication is not enabled. Available:[TOKEN]
at org.apache.hadoop.ipc.Client.call(Client.java:1411)
at org.apache.hadoop.ipc.Client.call(Client.java:1364)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:206)
at com.sun.proxy.$Proxy15.setSafeMode(Unknown Source)
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.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy15.setSafeMode(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.setSafeMode(ClientNamenodeProtocolTranslatorPB.java:602)
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.hbase.fs.HFileSystem$1.invoke(HFileSystem.java:279)
at com.sun.proxy.$Proxy16.setSafeMode(Unknown Source)
at org.apache.hadoop.hdfs.DFSClient.setSafeMode(DFSClient.java:2264)
at org.apache.hadoop.hdfs.DistributedFileSystem.setSafeMode(DistributedFileSystem.java:986)
at org.apache.hadoop.hdfs.DistributedFileSystem.setSafeMode(DistributedFileSystem.java:970)
at org.apache.hadoop.hbase.util.FSUtils.isInSafeMode(FSUtils.java:447)
at org.apache.hadoop.hbase.util.FSUtils.waitOnSafeMode(FSUtils.java:894)
at org.apache.hadoop.hbase.master.MasterFileSystem.checkRootDir(MasterFileSystem.java:416)
at org.apache.hadoop.hbase.master.MasterFileSystem.createInitialFileSystemLayout(MasterFileSystem.java:145)
at org.apache.hadoop.hbase.master.MasterFileSystem.<init>(MasterFileSystem.java:125)
at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:594)
at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:165)
at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1428)
at java.lang.Thread.run(Thread.java:745)
经过各方查找，最终发现问题是$HBASE_HOME/conf/hbase-site.xml中的如下属性配置错了：
<property>
<name>hbase.rootdir</name>
<value>hdfs://master:8020/hbase</value>
</property>
注：此配置中的IP或域名必须与$HADOOP_HOME/etc/hadoop/core-site.xml中的如下配置保持一致：
<property>
<name>fs.defaultFS</name>
<value>hdfs://master:8020</value>
</property>
总结：初入或者即使有经验的hadoop开发人员，在遇到类似错误时，也经常摸不着北，因为错误日志经常误导大家去其他地方查找问题。