hadoop.hdfs.server.namenode.SafeModeException:cannot delete ../mapred/system. name node is in safe mode

请参考：http://stackoverflow.com/questions/4966592/hadoop-safemode-recovery-taking-too-long

answer:“I had it once, where some blocks were never reported in. I had to forcefully let the namenode leave safemode (hadoop dfsadmin -safemode leave) and then run an fsck to delete missing files.”  

 这个提示我们在出现部分block找不到时会出现这种情况

 解决办法：启动hadoop之后执行命令 hadoop dfsadmin -safemode leave. 或者直接使用fsck命令删除缺失的block。