Multiple instances of Cassandra on each node in the cluster

Question

Is it possible to have a cluster in Cassandra where each of the server is running multiple instances of Cassandra(each instance is part of the same cluster).

I'm aware that if there's a single server in the cluster, then it's possible to run multiple instances of Cassandra on it, but is it also possible to have multiple such servers in the cluster. If yes, how will the configuration look like(listen address,ports etc)?

Even if it was possible, I understand that there might not be any performance benefits at all, just wanted to know if it's theoretically possible.

Answer 1

Yes, it's possible & such setup is often used for testing, for example, using CCM, although it creates multiple interfaces on loopback (127.0.0.2, ...). DataStax Enterprise also has so-called Multi-instance.

You need carefully configure your instances separating ports, etc. Right now, potentially using the Docker could be the simpler solution to implement it.

But why do you need to do it? Until you have really biffy machine, with a lot of RAM & multiple SSDs, this won't bring you additional performance.

Answer 2

Yes, it is possible even i have worked with 5 instance running in one server in production cluster. Trust me still it is still running but the generic issues i had is high GC all the time, dropped mutations and high latency so of course it is not good to have this kind of setup. but for your questions's answer yes it is possible and can be in production also.