The last decade has seen a proliferation in data storage technologies, from MongoDB to ElasticSearch to Riak to Datomic and so many others: relational databases, document stores, key-value stores… oh my! So many choices, so much confusion. While fundamentally different products, all of these solve the same age-old problem: that of storing and managing data on a persistent medium. Yet despite using them every day, we are often confounded by how they operate, treating them as magical devices that require special care. No more! They say a little knowledge is a dangerous thing… care to find out?