Scylla just eats all the ram it can with cache. So it's hard to say really. On Cassandra we allocated half the ram to the JVM which it gladly used up and left t

Scylla just eats all the ram it can with cache. So it's hard to say really. On Cassandra we allocated half the ram to the JVM which it gladly used up and left the other half to the OS for disk cache. On Scylla, since it uses direct io, there is no need for OS disk cache.