Quite a long time ago I worked on a system using Cassandra for storing some data. The system used about 100 gigabytes for data storage of Cassandra on all of the nodes in the cluster. At some point we needed to upgrade from version 2 to 3. I decided to take a backup using the included tooling of Cassandra. After taking a snapshot and compressing it, the size was 14 megabytes. I'm still in awe that this system existed.