在HDFS中，提供了fsck命令，用于检查HDFS上文件和目录的健康状态、获取文件的block信息和位置信息等。
fsck命令必须由HDFS超级用户来执行，普通用户无权限。
[hadoop@dev ~]$ hdfs fsckUsage: DFSck [-list-corruptfileblocks | [-move | -delete | -openforwrite] [-files [-blocks [-locations | -racks]]]] start checking from this path -move move corrupted files to /lost+found -delete delete corrupted files -files print out files being checked -openforwrite print out files opened for write -includeSnapshots include snapshot data if the given path indicates a snapshottable directory or there are snapshottable directories under it -list-corruptfileblocks print out list of missing blocks and files they belong to -blocks print out block report -locations print out locations for every block -racks print out network topology for data-node locations
- -move: 移动损坏的文件到/lost+found目录下
- -delete: 删除损坏的文件
- -files: 输出正在被检测的文件
- -openforwrite: 输出检测中的正在被写的文件
- -includeSnapshots: 检测的文件包括系统snapShot快照目录下的
- -list-corruptfileblocks: 输出损坏的块及其所属的文件
- -blocks: 输出block的详细报告
- -locations: 输出block的位置信息
- -racks: 输出block的网络拓扑结构信息
- -storagepolicies: 输出block的存储策略信息
- -blockId: 输出指定blockId所属块的状况,位置等信息
查看文件中损坏的块（-list-corruptfileblocks）
[hadoop@dev ~]$ hdfs fsck /hivedata/warehouse/liuxiaowen.db/lxw_product_names/ -list-corruptfileblocksThe filesystem under path '/hivedata/warehouse/liuxiaowen.db/lxw_product_names/' has 0 CORRUPT files
将损坏的文件移动至/lost+found目录（-move）
[hadoop@dev ~]$ hdfs fsck /hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00168 -moveFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00168 at Thu Aug 13 09:36:35 CST 2015.Status: HEALTHY Total size: 13497058 B Total dirs: 0 Total files: 1 Total symlinks: 0 Total blocks (validated): 1 (avg. block size 13497058 B) Minimally replicated blocks: 1 (100.0 %) Over-replicated blocks: 0 (0.0 %) Under-replicated blocks: 0 (0.0 %) Mis-replicated blocks: 0 (0.0 %) Default replication factor: 2 Average block replication: 2.0 Corrupt blocks: 0 Missing replicas: 0 (0.0 %) Number of data-nodes: 15 Number of racks: 1FSCK ended at Thu Aug 13 09:36:35 CST 2015 in 1 milliseconds The filesystem under path '/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00168' is HEALTHY
删除损坏的文件（-delete）
[hadoop@dev ~]$ hdfs fsck /hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00168 -deleteFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00168 at Thu Aug 13 09:37:58 CST 2015.Status: HEALTHY Total size: 13497058 B Total dirs: 0 Total files: 1 Total symlinks: 0 Total blocks (validated): 1 (avg. block size 13497058 B) Minimally replicated blocks: 1 (100.0 %) Over-replicated blocks: 0 (0.0 %) Under-replicated blocks: 0 (0.0 %) Mis-replicated blocks: 0 (0.0 %) Default replication factor: 2 Average block replication: 2.0 Corrupt blocks: 0 Missing replicas: 0 (0.0 %) Number of data-nodes: 15 Number of racks: 1FSCK ended at Thu Aug 13 09:37:58 CST 2015 in 1 milliseconds The filesystem under path '/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00168' is HEALTHY
检查并列出所有文件状态（-files）
[hadoop@dev ~]$ hdfs fsck /hivedata/warehouse/liuxiaowen.db/lxw_product_names/ -filesFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /hivedata/warehouse/liuxiaowen.db/lxw_product_names/ at Thu Aug 13 09:39:38 CST 2015/hivedata/warehouse/liuxiaowen.db/lxw_product_names/ dir/hivedata/warehouse/liuxiaowen.db/lxw_product_names/_SUCCESS 0 bytes, 0 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00000 13583807 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00001 13577427 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00002 13588601 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00003 13479213 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00004 13497012 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00005 13557451 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00006 13580267 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00007 13486035 bytes, 1 block(s): OK/hivedata/warehouse/liuxiaowen.db/lxw_product_names/part-00008 13481498 bytes, 1 block(s): OK...
检查并打印正在被打开执行写操作的文件（-openforwrite）
[hadoop@dev ~]$ hdfs fsck /hivedata/warehouse/liuxiaowen.db/lxw_product_names/ -openforwriteFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /hivedata/warehouse/liuxiaowen.db/lxw_product_names/ at Thu Aug 13 09:41:28 CST 2015.........................................................................................................................................................................................................Status: HEALTHY Total size: 2704782548 B Total dirs: 1 Total files: 201 Total symlinks: 0 Total blocks (validated): 200 (avg. block size 13523912 B) Minimally replicated blocks: 200 (100.0 %) Over-replicated blocks: 0 (0.0 %) Under-replicated blocks: 0 (0.0 %) Mis-replicated blocks: 0 (0.0 %) Default replication factor: 2 Average block replication: 2.0 Corrupt blocks: 0 Missing replicas: 0 (0.0 %) Number of data-nodes: 15 Number of racks: 1FSCK ended at Thu Aug 13 09:41:28 CST 2015 in 10 milliseconds The filesystem under path '/hivedata/warehouse/liuxiaowen.db/lxw_product_names/' is HEALTHY
打印文件的Block报告（-blocks）
需要和-files一起使用。
[hadoop@dev ~]$ hdfs fsck /logs/site/2015-08-08/lxw1234.log -files -blocksFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /logs/site/2015-08-08/lxw1234.log at Thu Aug 13 09:45:59 CST 2015/logs/site/2015-08-08/lxw1234.log 7408754725 bytes, 56 block(s): OK0. BP-1034052771-172.16.212.130-1405595752491:blk_1075892982_2152381 len=134217728 repl=21. BP-1034052771-172.16.212.130-1405595752491:blk_1075892983_2152382 len=134217728 repl=22. BP-1034052771-172.16.212.130-1405595752491:blk_1075892984_2152383 len=134217728 repl=23. BP-1034052771-172.16.212.130-1405595752491:blk_1075892985_2152384 len=134217728 repl=24. BP-1034052771-172.16.212.130-1405595752491:blk_1075892997_2152396 len=134217728 repl=25. BP-1034052771-172.16.212.130-1405595752491:blk_1075892998_2152397 len=134217728 repl=26. BP-1034052771-172.16.212.130-1405595752491:blk_1075892999_2152398 len=134217728 repl=27. BP-1034052771-172.16.212.130-1405595752491:blk_1075893000_2152399 len=134217728 repl=28. BP-1034052771-172.16.212.130-1405595752491:blk_1075893001_2152400 len=134217728 repl=29. BP-1034052771-172.16.212.130-1405595752491:blk_1075893002_2152401 len=134217728 repl=210. BP-1034052771-172.16.212.130-1405595752491:blk_1075893003_2152402 len=134217728 repl=211. BP-1034052771-172.16.212.130-1405595752491:blk_1075893004_2152403 len=134217728 repl=212. BP-1034052771-172.16.212.130-1405595752491:blk_1075893005_2152404 len=134217728 repl=213. BP-1034052771-172.16.212.130-1405595752491:blk_1075893006_2152405 len=134217728 repl=214. BP-1034052771-172.16.212.130-1405595752491:blk_1075893007_2152406 len=134217728 repl=2...
其中，/logs/site/2015-08-08/lxw1234.log 7408754725 bytes, 56 block(s): 表示文件的总大小和block数；
0. BP-1034052771-172.16.212.130-1405595752491:blk_1075892982_2152381 len=134217728 repl=2
1. BP-1034052771-172.16.212.130-1405595752491:blk_1075892983_2152382 len=134217728 repl=2 2. BP-1034052771-172.16.212.130-1405595752491:blk_1075892984_2152383 len=134217728 repl=2前面的0. 1. 2.代表该文件的block索引，56的文件块，就从0-55;
BP-1034052771-172.16.212.130-1405595752491:blk_1075892982_2152381表示block id；
len=134217728 表示该文件块大小；
repl=2 表示该文件块副本数；
打印文件块的位置信息（-locations）
需要和-files -blocks一起使用。
[hadoop@dev ~]$ hdfs fsck /logs/site/2015-08-08/lxw1234.log -files -blocks -locationsFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /logs/site/2015-08-08/lxw1234.log at Thu Aug 13 09:45:59 CST 2015/logs/site/2015-08-08/lxw1234.log 7408754725 bytes, 56 block(s): OK0. BP-1034052771-172.16.212.130-1405595752491:blk_1075892982_2152381 len=134217728 repl=2 [172.16.212.139:50010, 172.16.212.135:50010]1. BP-1034052771-172.16.212.130-1405595752491:blk_1075892983_2152382 len=134217728 repl=2 [172.16.212.140:50010, 172.16.212.133:50010]2. BP-1034052771-172.16.212.130-1405595752491:blk_1075892984_2152383 len=134217728 repl=2 [172.16.212.136:50010, 172.16.212.141:50010]3. BP-1034052771-172.16.212.130-1405595752491:blk_1075892985_2152384 len=134217728 repl=2 [172.16.212.133:50010, 172.16.212.135:50010]4. BP-1034052771-172.16.212.130-1405595752491:blk_1075892997_2152396 len=134217728 repl=2 [172.16.212.142:50010, 172.16.212.139:50010]5. BP-1034052771-172.16.212.130-1405595752491:blk_1075892998_2152397 len=134217728 repl=2 [172.16.212.133:50010, 172.16.212.139:50010]6. BP-1034052771-172.16.212.130-1405595752491:blk_1075892999_2152398 len=134217728 repl=2 [172.16.212.141:50010, 172.16.212.135:50010]7. BP-1034052771-172.16.212.130-1405595752491:blk_1075893000_2152399 len=134217728 repl=2 [172.16.212.144:50010, 172.16.212.142:50010]8. BP-1034052771-172.16.212.130-1405595752491:blk_1075893001_2152400 len=134217728 repl=2 [172.16.212.133:50010, 172.16.212.138:50010]9. BP-1034052771-172.16.212.130-1405595752491:blk_1075893002_2152401 len=134217728 repl=2 [172.16.212.140:50010, 172.16.212.134:50010]
和打印出的文件块信息相比，多了一个文件块的位置信息：[172.16.212.139:50010, 172.16.212.135:50010]
打印文件块位置所在的机架信息（-racks）
[hadoop@dev ~]$ hdfs fsck /logs/site/2015-08-08/lxw1234.log -files -blocks -locations -racksFSCK started by hadoop (auth:SIMPLE) from /172.16.212.17 for path /logs/site/2015-08-08/lxw1234.log at Thu Aug 13 09:45:59 CST 2015/logs/site/2015-08-08/lxw1234.log 7408754725 bytes, 56 block(s): OK0. BP-1034052771-172.16.212.130-1405595752491:blk_1075892982_2152381 len=134217728 repl=2 [/default-rack/172.16.212.139:50010, /default-rack/172.16.212.135:50010]1. BP-1034052771-172.16.212.130-1405595752491:blk_1075892983_2152382 len=134217728 repl=2 [/default-rack/172.16.212.140:50010, /default-rack/172.16.212.133:50010]2. BP-1034052771-172.16.212.130-1405595752491:blk_1075892984_2152383 len=134217728 repl=2 [/default-rack/172.16.212.136:50010, /default-rack/172.16.212.141:50010]3. BP-1034052771-172.16.212.130-1405595752491:blk_1075892985_2152384 len=134217728 repl=2 [/default-rack/172.16.212.133:50010, /default-rack/172.16.212.135:50010]4. BP-1034052771-172.16.212.130-1405595752491:blk_1075892997_2152396 len=134217728 repl=2 [/default-rack/172.16.212.142:50010, /default-rack/172.16.212.139:50010]5. BP-1034052771-172.16.212.130-1405595752491:blk_1075892998_2152397 len=134217728 repl=2 [/default-rack/172.16.212.133:50010, /default-rack/172.16.212.139:50010]
和前面打印出的信息相比，多了机架信息：[/default-rack/172.16.212.139:50010, /default-rack/172.16.212.135:50010]