hadoop Safe mode is ON 的解决办法

搭了一个hadoop集群环境，近期总是出现读写文件错误的情况，查看name node的日志显示 （ Safe mode is ON）

 Safe mode is ON. The ratio of reported blocks 0.2000 has not reached the threshold 0.9990. Safe mode will be turned off automatically.

再往上翻

 org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot delete /home/hadoop/tmp/mapred/system. Name node is in safe mode.

google 解决方案有三种

1）执行命令：bin/hadoop dfsadmin -safemode leave

dfsadmin -safemode value 参数value的说明如下：

enter - 进入安全模式

leave - 强制NameNode离开安全模式

get -  返回安全模式是否开启的信息

wait - 等待安全模式结束。

2）重新格式化文件系统 =。=

3）bin/hadoop fsck /

第一种方法，需要每次都执行一遍，很纠结~

第二种方法，format的意思你懂得。。。。

第三种方法，如果数据多，那执行起来会很慢，没办法，慢慢等吧。

 hadoop@mhadoop:~/hadoop-1.0.0$ bin/hadoop fsck /
 FSCK started by hadoop from /192.168.1.110 for path / at Wed Mar 07 17:57:43 CST 2012
 .
 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0001/job.jar: CORRUPT block blk_-8710406465335110666

 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0001/job.jar: MISSING 1 blocks of total size 142465 B..
 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0002/job.jar: CORRUPT block blk_8343735010139595189

 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0002/job.jar: MISSING 1 blocks of total size 142465 B..
 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0004/job.jar: CORRUPT block blk_4796918520991551976

 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0004/job.jar: MISSING 1 blocks of total size 142465 B..
 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0005/job.jar: CORRUPT block blk_8732649167016211914

 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0005/job.jar: MISSING 1 blocks of total size 142465 B..
 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0006/job.jar: CORRUPT block blk_2190395249671123528

 /tmp/hadoop/tmp/mapred/staging/hadoop/.staging/job_201202290728_0006/job.jar: MISSING 1 blocks of total size 142465 B..
 /tmp/hadoop/tmp/mapred/system/jobtracker.info: Under replicated blk_3010497672022840180_1511. Target Replicas is 2 but found 1 replica(s).
 .
 /user/hadoop/input/README.txt: Under replicated blk_1278803782511847062_1510. Target Replicas is 2 but found 1 replica(s).
 ..
 /user/hadoop/output/_logs/history/job_201202290728_0007_1330473591943_hadoop_word+count: CORRUPT block blk_-165491155081655193

 /user/hadoop/output/_logs/history/job_201202290728_0007_1330473591943_hadoop_word+count: MISSING 1 blocks of total size 13581 B..
 /user/hadoop/output/_logs/history/job_201202290728_0007_conf.xml: CORRUPT block blk_359906738089887519

 /user/hadoop/output/_logs/history/job_201202290728_0007_conf.xml: MISSING 1 blocks of total size 20344 B..
 /user/hadoop/output/part-r-00000: CORRUPT block blk_-3883649133311907523

 /user/hadoop/output/part-r-00000: MISSING 1 blocks of total size 158081 B.Status: CORRUPT
 Total size: 905701 B
 Total dirs: 20
 Total files: 11
 Total blocks (validated): 10 (avg. block size 90570 B)
 ********************************
 CORRUPT FILES: 8
 MISSING BLOCKS: 8
 MISSING SIZE: 904331 B
 CORRUPT BLOCKS: 8
 ********************************
 Minimally replicated blocks: 2 (20.0 %)
 Over-replicated blocks: 0 (0.0 %)
 Under-replicated blocks: 2 (20.0 %)
 Mis-replicated blocks: 0 (0.0 %)
 Default replication factor: 2
 Average block replication: 0.2
 Corrupt blocks: 8
 Missing replicas: 2 (100.0 %)
 Number of data-nodes: 1
 Number of racks: 1
 FSCK ended at Wed Mar 07 17:57:43 CST 2012 in 11 milliseconds


 The filesystem under path '/' is CORRUPT