Do you need to restart daemons when you change cluster properties in hadoop?

Question

Say, by default, the replication rate is 3, and I would like to know if we change the replication rate to 2, do I have to restart hadoop daemons for the changes to take effect?

If so, is there any specific reason why this was done?

Another way to solve problems may arise if you say that the configuration will be applied without having to restart the hadoop cluster?

Answer 1

https://hadoop.apache.org/docs/r0.18.3/hdfs_shell.html

The definition of the following command:

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

Changes the replication factor of a file. -R option is for recursively increasing the replication     factor of files within a directory.

Example:

hadoop fs -setrep -w 3 -R /user/hadoop/dir1
Exit Code:

Returns 0 on success and -1 on error.

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