in 1.2 bloom filters and compression meta data were moved off heap. in 2.0 index samples were also taken off heap.
Row cache has been off heap for a while, and the key cache is still on heap.
Any other components you were interested in ?
The best reference will be the NEWS.txt file and the blog posts at datastax.
Co-Founder & Principal Consultant
Apache Cassandra Consulting
Solely by the Cassandra version. Are you asking about a particular component not mentioned above?
Not exactly. From version to version, the component of cassandra may reside on heap or off heap, so is there a way to determine which component in the cassandra version that may reside on heap or off heap?