hive> select * from c; 
FAILED: RuntimeException org.apache.hadoop.ipc.RemoteException: org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot create directory /tmp/hive-root/hive_2013-09-12_05-28-29_286_5210437459106402365. Name node is in safe mode.
The ratio of reported blocks 0.6857 has not reached the threshold 0.9990. Safe mode will be turned off automatically.
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirsInternal(FSNamesystem.java:2055)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.mkdirs(FSNamesystem.java:2029)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.mkdirs(NameNode.java:817)
        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.ipc.RPC$Server.call(RPC.java:563)
        at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388)
        at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:415)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1382)
 

解決辦法：關閉安全模式

hadoop dfsadmin -safemode leave