hadoop fsck命令详解

吴贺华

　　hadoop  fsck
　　
Usage: DFSck <path> [-move | -delete | -openforwrite] [-files [-blocks [-locations | -racks]]]
        <path>             检查这个目录中的文件是否完整
　　-move               破损的文件移至/lost+found目录
        -delete             删除破损的文件
　　-openforwrite   打印正在打开写操作的文件
　　-files                 打印正在check的文件名
　　-blocks             打印block报告 （需要和-files参数一起使用）
　　-locations         打印每个block的位置信息（需要和-files参数一起使用）
　　-racks               打印位置信息的网络拓扑图 （需要和-files参数一起使用）
　　hadoop  fsck /
　　
　　用这个命令可以检查整个文件系统的健康状况，但是要注意它不会主动恢复备份缺失的block，这个是由NameNode单独的线程异步处理的。
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/user/distribute-hadoop-boss/tmp/pgv/20090813/1000000103/input/JIFEN.QQ.COM.2009-08-13-18.30:  Replica placement policy is violated for blk_7596595208988121840_5377589. Block should be additionally replicated on 1 more rack(s).
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/user/distribute-hadoop-boss/tmp/pgv/20090813/1000000310/input/PAY.QQ.COM.2009-08-13-20.30:  Replica placement policy is violated for blk_8146588794511444453_5379501. Block should be additionally replicated on 1 more rack(s).
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.........................................................................................Status: HEALTHY
 Total size:    5042961147529 B (Total open files size: 1610612736 B)
 Total dirs:    723
 Total files:   128089 (Files currently being written: 2)
 Total blocks (validated):      171417 (avg. block size 29419259 B) (Total open file blocks (not validated): 24)
 Minimally replicated blocks:   171417 (100.0 %)
 Over-replicated blocks:        0 (0.0 %)
 Under-replicated blocks:       0 (0.0 %)
 Mis-replicated blocks:         476 (0.2776854 %)
 Default replication factor:    3  缺省的备份参数3
 Average block replication:     3.000146
 Corrupt blocks:                0     破损的block数0
 Missing replicas:              0 (0.0 %)
 Number of data-nodes:          107
 Number of racks:               4
　　
The filesystem under path '/' is HEALTHY
　　hadoop  fsck /user/distribute-hadoop-boss/tmp/pgv/20090813/1000000103/input/JIFEN.QQ.COM.2009-08-13-18.30 -files -blocks -locations  -racks
　　打印出了这个文件每个block的详细信息包括datanode的机架信息。
　　
/user/distribute-hadoop-boss/tmp/pgv/20090813/1000000103/input/JIFEN.QQ.COM.2009-08-13-18.30 74110492 bytes, 2 block(s):  Replica placement policy is violated for blk_7596595208988121840_5377589. Block should be additionally replicated on 1 more rack(s).  这个block虽然有三份拷贝，但是都在一个rack里，应该有一个副本放在不同的机架，详细见上一节（副本放置策略）
　　0. blk_-4839761191731553520_5377588 len=67108864 repl=3 [/lg/dminterface0/172.16.236.158:50010, /lg/dminterface1/172.16.218.108:50010, /lg/dminterface1/172.16.236.36:50010]
　　1. blk_7596595208988121840_5377589 len=7001628 repl=3  [/lg/dminterface2/172.16.236.51:50010, /lg/dminterface2/172.16.218.217:50010, /lg/dminterface2/172.16.218.200:50010]
　　三份拷贝的datanode信息,都在/lg/dminterface2里
　　Status: HEALTHY
 Total size:    74110492 B
 Total dirs:    0
 Total files:   1
 Total blocks (validated):      2 (avg. block size 37055246 B)
 Minimally replicated blocks:   2 (100.0 %)
 Over-replicated blocks:        0 (0.0 %)
 Under-replicated blocks:       0 (0.0 %)
 Mis-replicated blocks:         1 (50.0 %)
 Default replication factor:    3
 Average block replication:     3.0
 Corrupt blocks:                0
 Missing replicas:              0 (0.0 %)
 Number of data-nodes:          107
 Number of racks:               4
　　
The filesystem under path '/user/distribute-hadoop-boss/tmp/pgv/20090813/1000000103/input/JIFEN.QQ.COM.2009-08-13-18.30' is HEALTHY