The first 6 months were rough. The cluster had been in operation for more than 6 months but was not doing too well. Performance was poor and, worse, it frequently crashed. It was not a fun time. But eventually, the problems got fixed.
There were several issues (including my inexperience) that caused these problems, but the core one was that the original developer had treated it like another relational database.
Read on for a few tips to make learning (and managing) Apache Cassandra a little easier.