HDFS space usage on fresh install

问题

I just installed HDFS and launched the service,
and there is already more than 800MB of used space.

What does it represent ?

$ hdfs dfs -df -h
Filesystem                         Size     Used  Available  Use%
hdfs://quickstart.cloudera:8020  54.5 G  823.7 M     43.4 G    1%

来源：https://stackoverflow.com/questions/43165646/hdfs-space-usage-on-fresh-install