It seems Cassandra creates a big pile of threads for different tasks, I didn’t step into details, but I’m pretty sure it has more than 40 threads with default setting on a 2-nodes cluster. So multi core may not be a concern, as all these threads can run on different cores to fully utilize the CPU resource.
However, my tests show something really worry me – multi-node cluster performs worse than single node (due to inter-node communication I believe), and multi-cores deployment is slower than single-core deployment (this is something I don’t quite understand, may be because of L1/L2 cache?).
I need some hardware to test it as well, as VM is not that good for this kind of test. Then I suddenly recall I still have some 8-core/16G boxes in company sitting idle there, I can use one or two to do the test for sure 😉