我在8节点集群上部署了hadoop（0.20.203.0rc1）。将文件上传到hdfs之后，我只在其中一个节点上获取此文件，而不是在所有节点上均匀分布。可能是什么问题？
$HADOOP_HOME/bin/hadoop dfs -copyFromLocal ../data/rmat-20.0 /user/frolo/input/rmat-20.0
$HADOOP_HOME/bin/hadoop dfs -stat "%b %o %r %n" /user/frolo/input/rmat-*
1220222968 67108864 1 rmat-20.0
$HADOOP_HOME/bin/hadoop dfsadmin -report
Configured Capacity: 2536563998720 (2.31 TB)
Present Capacity: 1642543419392 (1.49 TB)
DFS Remaining: 1641312030720 (1.49 TB)
DFS Used: 1231388672 (1.15 GB)
DFS Used%: 0.07%
Under replicated blocks: 0
Blocks with corrupt replicas: 0
Missing blocks: 0
-------------------------------------------------
Datanodes available: 8 (8 total, 0 dead)
Name: 10.10.1.15:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 131536928768 (122.5 GB)
DFS Remaining: 185533546496(172.79 GB)
DFS Used%: 0%
DFS Remaining%: 58.51%
Last contact: Fri Feb 07 12:10:27 MSK 2014
Name: 10.10.1.13:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 131533377536 (122.5 GB)
DFS Remaining: 185537097728(172.79 GB)
DFS Used%: 0%
DFS Remaining%: 58.52%
Last contact: Fri Feb 07 12:10:27 MSK 2014
Name: 10.10.1.17:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 120023924736 (111.78 GB)
DFS Remaining: 197046550528(183.51 GB)
DFS Used%: 0%
DFS Remaining%: 62.15%
Last contact: Fri Feb 07 12:10:27 MSK 2014
Name: 10.10.1.18:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 78510628864 (73.12 GB)
DFS Remaining: 238559846400(222.18 GB)
DFS Used%: 0%
DFS Remaining%: 75.24%
Last contact: Fri Feb 07 12:10:24 MSK 2014
Name: 10.10.1.14:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 131537530880 (122.5 GB)
DFS Remaining: 185532944384(172.79 GB)
DFS Used%: 0%
DFS Remaining%: 58.51%
Last contact: Fri Feb 07 12:10:27 MSK 2014
Name: 10.10.1.11:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 1231216640 (1.15 GB)
Non DFS Used: 84698116096 (78.88 GB)
DFS Remaining: 231141167104(215.27 GB)
DFS Used%: 0.39%
DFS Remaining%: 72.9%
Last contact: Fri Feb 07 12:10:24 MSK 2014
Name: 10.10.1.16:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 131537494016 (122.5 GB)
DFS Remaining: 185532981248(172.79 GB)
DFS Used%: 0%
DFS Remaining%: 58.51%
Last contact: Fri Feb 07 12:10:27 MSK 2014
Name: 10.10.1.12:50010
Decommission Status : Normal
Configured Capacity: 317070499840 (295.29 GB)
DFS Used: 24576 (24 KB)
Non DFS Used: 84642578432 (78.83 GB)
DFS Remaining: 232427896832(216.47 GB)
DFS Used%: 0%
DFS Remaining%: 73.3%
Last contact: Fri Feb 07 12:10:27 MSK 2014
答案 0 :(得分：1)
您的文件使用1的复制因子编写，由hadoop fs -stat命令输出证明。这意味着文件下的块只存在一个块副本。
写入的默认复制因子由dfs.replication下的属性$HADOOP_HOME/conf/hdfs-site.xml控制。如果未在其下指定，则默认值为3，但您可能已指定其值为1的覆盖。将其值更改回3或完全删除它（以调用默认值）将使所有新文件写入默认使用3个副本。
您还可以使用-D实用程序支持的hadoop fs属性传递方法，使用每个写入命令传递特定的复制因子，例如：
hadoop fs -Ddfs.replication=3 -copyFromLocal ../data/rmat-20.0 /user/frolo/input/rmat-20.0
您可以使用hadoop fs -setrep实用程序更改现有文件的复制因子，例如：
hadoop fs -setrep 3 -w /user/frolo/input/rmat-20.0
HDFS 复制因子大于1的文件将自动显示在多个节点上。 HDFS永远不会将一个块的多个副本写入同一个DataNode。