命令修改副本数：hadoop fs -setrep

setrep

Usage: hadoop fs -setrep [-R] [-w] <numReplicas> <path>

Changes the replication factor of a file. If path is a directory then the command recursively
changes the replication factor of all files under the directory tree rooted at path.

Options:

The -w flag requests that the command wait for the replication to complete. This can potentially take a very long time.
The -R flag is accepted for backwards compatibility. It has no effect.

Example:

    hadoop fs -setrep -w 3 /user/hadoop/dir1

Exit Code:

Returns 0 on success and -1 on error.

[root@node1 ~]# hadoop fs -ls /test
18/01/23 01:24:46 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 4 items
-rw-r--r--   3 root hbase  100797385 2018-01-22 22:26 /test/a.tar
-rw-r--r--   3 root hbase  100854145 2018-01-22 22:26 /test/a.zip
-rw-r--r--   3 root hbase   38009648 2018-01-22 22:27 /test/kafka-2.10-0.10.2.0.x86_64.rpm
-rw-r--r--   3 root hbase    2374608 2018-01-22 22:27 /test/zookeeper-3.4.6-1.x86_64.rpm
[root@node1 ~]# 

[root@node1 ~]# hadoop fs -setrep -w 2 /test
18/01/23 01:24:58 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Replication 2 set: /test/a.tar
Replication 2 set: /test/a.zip
Replication 2 set: /test/kafka-2.10-0.10.2.0.x86_64.rpm
Replication 2 set: /test/zookeeper-3.4.6-1.x86_64.rpm
Waiting for /test/a.tar ...
WARNING: the waiting time may be long for DECREASING the number of replications.
. done
Waiting for /test/a.zip ... done
Waiting for /test/kafka-2.10-0.10.2.0.x86_64.rpm ... done
Waiting for /test/zookeeper-3.4.6-1.x86_64.rpm ... done
[root@node1 ~]# 

[root@node1 ~]# hadoop fs -ls /test
18/01/23 01:25:12 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 4 items
-rw-r--r--   2 root hbase  100797385 2018-01-22 22:26 /test/a.tar
-rw-r--r--   2 root hbase  100854145 2018-01-22 22:26 /test/a.zip
-rw-r--r--   2 root hbase   38009648 2018-01-22 22:27 /test/kafka-2.10-0.10.2.0.x86_64.rpm
-rw-r--r--   2 root hbase    2374608 2018-01-22 22:27 /test/zookeeper-3.4.6-1.x86_64.rpm
[root@node1 ~]#