Changing the replication factor of an existing file in HDFS

In this recipe, we are going to take a look at how to change the replication factor of a file in HDFS. The default replication factor is 3.

Getting ready

To perform this recipe, you should already have a running Hadoop cluster.

How to do it...

Sometimes. there might be a need to increase or decrease the replication factor of a specific file in HDFS. In this case, we'll use the setrep command.

This is how you can use the command:

hadoop fs -setrep [-R] [-w] <noOfReplicas><path> ...

In this command, a path can either be a file or directory; if its a directory, then it recursively sets the replication factor for all replicas.

• The w option flags the command and should wait until the replication is complete
• The r option is accepted for backward compatibility

First, let's check the replication factor of the file we copied to HDFS in the previous recipe:

hadoop fs -ls /mydir1/LICENSE.txt
-rw-r--r--   3 ubuntu supergroup  ...