linux-filesystems

 By default, the ext3 and ext4 filesystems reserve 5% space for use by the root user. This reserved space counts as Non DFS Used.

To view the reserved space use the tune2fs command.
$ sudo lsblk  
sudo tune2fs -l /dev/nvme0n1p1 | egrep "Block count|Reserved block count"

OUTPUT :
Reserved block count: 36628312
Block size:      4096

The Reserved block count is the number of ext3/ext4 filesystem blocks that are reserved. The block size is the size in bytes.

Cloudera recommends reducing the root user block reservation from 5% to 1% for the DataNode volumes.

To set reserved space to 1% with the tune2fs command

tune2fs -m 1 /dev/sde1

run the following command to see output

$ sudo tune2fs -l /dev/nvme0n1p1 | egrep "Block count|Reserved block count"