Deleting files from HDFS does not free up disk space
I found a similar issue on our cluster, which stemmed probably from a failed upgrade.
First make sure to finalize the upgrade on the namenode
hdfs dfsadmin -finalizeUpgradeWhat I found was that the datanodes for some reason did not finalize their directories at all.
On your datanode, you should see the following directory layout
/[mountpoint}/dfs/dn/current/{blockpool}/currentAnd
/[mountpoint}/dfs/dn/current/{blockpool}/previousIf you have not finalized the previous directory contains all data that was created before the update. If you delete anything it will not remove it - hence your storage never reduces.
Actually the most simplest solution was sufficient
Restart the namenode
Watch the log of the datanode, you should see something like this
INFO org.apache.hadoop.hdfs.server.common.Storage: Finalizing upgrade for storage directoryAfterwards the directories will be cleared in the background and the storage reclaimed.