service not work on hadoop cdh3

[Thomas-Tsai]

the error message like
2013-11-21 12:10:37,490 ERROR org.apache.hadoop.security.UserGroupInformation: PriviledgedActionException as:mapred (auth:SIMPLE) cause:org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot set permission for /var/lib/hadoop-0.20/cache/mapred/mapred/system. Name node is in safe mode.
The number of live datanodes 0 needs an additional 1 live datanodes to reach the minimum number 1. Safe mode will be turned off automatically.
2013-11-21 12:10:37,492 INFO org.apache.hadoop.ipc.Server: IPC Server handler 6 on 8020, call setPermission(/var/lib/hadoop-0.20/cache/mapred/mapred/system, rwx------) from 10.0.0.254:44369: error: org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot set permission for /var/lib/hadoop-0.20/cache/mapred/mapred/system. Name node is in safe mode.

after manual create folder and set permission to 700, the name node work fine.