Hello @Giovannas,
Welcome to Communities.
"Does VMware VSAN require all nodes to have the same hardware configurations, and be the same brand?"
*Technically* no, the nodes do not need identical hardware - all that is required is that all nodes components are supported for the version of ESXi (5.5, 6.0, 6.5) and that the RAID/HBA controllers, cache-tier SSD/NVMe and capacity tier SSD/HDD are on the vSAN-specific HCL:
https://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan
(Click 'Build Your Own based on Certified Components.' if not looking at ReadyNodes)
However, best practice is to have all aspects of each node identical (e.g. make/model of server, drives, controllers, number of disks and disk-groups). If you are considering building a mix & match cluster then do at least ensure they are of similar spec.
"What are the pre-requisites for a 3 node configuration"
For Hybrid:
Dedicated 1GB uplink(s).
vSAN and vSphere licensing.
Server supported for the version of ESXi.
At least one vSAN-supported controller, SSD/NVMe and HDD per node.
For All-Flash:
Shared 10GB uplink(s).
vSAN and vSphere licensing.
Server supported for the version of ESXi.
At least one vSAN-supported controller, SSD/NVMe and capacity-SSD per node.
Bob
