Scylla has also stalled in support of features that Cassandra offers, which is strange because they came out of the gates like gangbusters. It is not the drop in replacement they advertise.

But I'm not going to tell you "don't use scylladb". They have lots of educational whitepapers for maxing I/O and hardware that apply both to cassandra and scylladb.

The biggest thing with cassandra and scylla is that you need a technical management to understand the headaches, and appreciate the silent benefits. Cassandra places often have frustrated management about the cassandra management problems, but when I ask "has your cluster ever gone down?" and they say no, even across major version upgrades and the like, expansions, etc.

Also keep in mind that cassandra also has a tendency to make your big data bigger with timestamps-per-cell, replicas, etc.