See also cassandra-glossary
"It's traditional wisdom that Cassandra and AWS EBS don't mix." (#)
Does Instaclustr offer custom EBS sizes? No. EBS cost is a small proportion of the overall cost of a node. For manageability we stick to a specified set of sizes where we know the performance characteristics of every size we offer. (#)
"Use only ephemeral instance-store or the recommended EBS volume types for Cassandra data storage." (#)
At 33:30 If you want 'insert if it does not exist' semantics, Cassandra uses Paxos for distrubuted locking. It is a read-before-write with the locking provided by the database. (#)