Waiting for dfs to exit safe mode...

1、启动Hbase之前尽量关闭Hadoop的HDFS的安全模式，未关闭可能会造成Hbase在HDFS上创建文件不成功，日志记录中也会出现如下记录：

2012-04-10 21:37:01,999 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:37:12,003 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:37:22,006 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:37:32,011 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:37:42,014 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:37:52,019 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:38:02,022 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:38:12,029 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:38:22,032 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...
2012-04-10 21:38:32,036 INFO org.apache.hadoop.hbase.util.FSUtils: Waiting for dfs to exit safe mode...

解决方法：使用 hadoop dfsadmin -safemode leave 命令使Hadoop退出安全模式。