Solved
HDFS data is not decreasing after reducing the replication from 3 to 2
I reduced the replication factor of my HDFS data from 3 to 2, but I noticed that the total data size and storage space are still not decreasing as expected
SheltonAnswer
Gold ⭐️⭐️⭐️
February 7, 2019
The below command sets your replication factor to 1 for all new files you will create, with a potential data loss unless you are running HDP 3.x which has a new HDFS algorithm EC erasure coding
$ hdfs dfs -setrep -w 1 -R /
As responded above the changes only affect new files you will create. After changing the replication factor you won't see any hdfs size changes until the trash time interval which was set on 360 minutes configured by the hdfs trash interval has been reached
fs.trash.interval
Once the NameNode metadata has been updated, it is the DataNodes which would actually do the operation. There could be some delay, but space is definitely reclaimed.
HTH
