Storage for nodes

hi, I am trying to setup a small fully virtualized cluster consisting of 3 nodes. I use VMware and centos 6.6.
My problem is basically how to deploy storage. Each node has 16TB local storage as single volume.
I am thinking of deploying 1vm(ambari) 3 vms (namenode,resourcemanager and hbase master) and 30vms(slaves-workers).
How much storage is considered good for every single vm ? There is no shared storage device (nas-san).
Should I have separate volumes for os installation and hdfs data ?
Thank you.