Configurating druid services with 3 nodes of all (4 CPU, 8 GB RAM)

Hi all,

I am trying to setup a small druid cluster, I can use 3 VMs and 32 GB RAM and 12 CPUs in total.
So the plan is

1st VM:
(4 CPU, 8 GB, 100G Disk) :- coordinator, Overlord and zookeeper.

2nd VM:

(4 CPU, 8 GB, 100G DIsk) :- historical, middlemanager

3rd VM:

(4 CPU, 8 GB, 100G Disk) :- broker

Is this fine? or should we make any changes to the specs?
Apart from that I was wondering what should be the druid.server.http.numThreads, druid.processing.buffer.sizeBytes and druid.processing.numThreads for broker, middlemanager and historical

Any suggestions or advices on this please?