Trade-off factors while designing scale up and scale out clusters
You should take an initial design decision when you design your vSphere HA cluster. Now the decision is whether you should design a small cluster with larger hosts, or a large cluster with smaller hosts.
We call the first cluster as scale up cluster, and the second one as scale out cluster. There are many factors that work as a catalyst when you choose a scale up or a scale out cluster. Some of them are as follows:
Depending on the cost, which hardware is ideal for lowering cost, a few larger hosts or a large number of smaller hosts? Though this answer varies in different situations.
What is the operational cost and complexity over the period of time in maintaining any of these two models?
What about the other infrastructure components, such as power, cooling, and floor space?
What is the purpose of this cluster? Is it a Desktop Virtualization Cluster or a Server Virtualization Cluster?
The design decision that you choose depends...