Good morning,

I currently have an Openstack cluster made up of 3 nodes, an iscsi bay (10T), 576 G of Ram, 10T, 288vcpus. 

This cluster is used by around 150 students, but is reaching its limits.

Having obtained a budget to set up a larger cluster, I am wondering about the choice of the number of nodes, their role (how many controllers, network, compute, etc.) and above all what solution for storage.

Let's imagine a budget to buy 6 servers with good capacities, is the right choice Ceph storage (with cinder and rdb?) on the Openstack cluster nodes? Do we need 3 servers for a Ceph cluster and 3 for the Openstack part (in this case I lose capacity for the "compute" part)... I don't know what the right choices are and above all, I have a little afraid of going in the wrong directions.

Could any of you guide me, or give me links to sites that could help me (and that I haven't seen).

Thanks in advance