How much free space do I need to rebalance a HDFS data node?

[#1]

I have a HDFS data node that has reached 100% disk usage and has completely filled a disk. Some of the other data nodes in the cluster have very lo utilisation (<20%). I would like to rebalance the cluster but since the disk is at 100% it doesn't seem to be able to rebalance. How much free space do I need to have on a data node in order for HDFS to rebalance it?

[#2]

The above was originally posted in the Community Help Track. On Wed May 22 03:25 UTC 2019, a member of the HCC moderation staff moved it to the Hadoop Core Track. The Community Help Track is intended for questions about using the HCC site itself.