EC2 AMI does not persist data to disk

Hi there,

N00b Couchbase user here, I have a dataset of about 7GB JSON and after loading this data set I am a little confused by the numbers that I see in the dashboard:
RAM: 2.7GB use, 4.8GB free
Disk: 800MB use, 70GB free

Does Couchbase perform some magic compression on the data set?