转自：http://lxw1234.com/archives/2015/08/452.htm
hdfs fsck命令查看HDFS文件对应的文件块信息(Block)和位置信息(Locations)
关键字：hdfs fsck、block、locations
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 fsck
Usage: 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
下面介绍每一个选项的含义及用法。
查看文件中损坏的块（-list-corruptfileblocks）
[hadoop@dev ~]$ hdfs fsck /hivedata/warehouse/liuxiaowen.db/lxw_product_names/ -list-corruptfileblocks
The 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 -move
FSCK 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: 1
FSCK 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 -delete
FSCK 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: 1
FSCK 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/ -files
FSCK 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/ -openforwrite
FSCK 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: 1
FSCK 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 -blocks
FSCK 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): OK
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
3. BP-1034052771-172.16.212.130-1405595752491:blk_1075892985_2152384 len=134217728 repl=2
4. BP-1034052771-172.16.212.130-1405595752491:blk_1075892997_2152396 len=134217728 repl=2
5. BP-1034052771-172.16.212.130-1405595752491:blk_1075892998_2152397 len=134217728 repl=2
6. BP-1034052771-172.16.212.130-1405595752491:blk_1075892999_2152398 len=134217728 repl=2
7. BP-1034052771-172.16.212.130-1405595752491:blk_1075893000_2152399 len=134217728 repl=2
8. BP-1034052771-172.16.212.130-1405595752491:blk_1075893001_2152400 len=134217728 repl=2
9. BP-1034052771-172.16.212.130-1405595752491:blk_1075893002_2152401 len=134217728 repl=2
10. BP-1034052771-172.16.212.130-1405595752491:blk_1075893003_2152402 len=134217728 repl=2
11. BP-1034052771-172.16.212.130-1405595752491:blk_1075893004_2152403 len=134217728 repl=2
12. BP-1034052771-172.16.212.130-1405595752491:blk_1075893005_2152404 len=134217728 repl=2
13. BP-1034052771-172.16.212.130-1405595752491:blk_1075893006_2152405 len=134217728 repl=2
14. 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 -locations
FSCK 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): OK
0. 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 -racks
FSCK 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): OK
0. 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]