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VMware vSphere 6.5 Update 1 has been released on July 27, 2017 with several bug fix, some improvements, but also some interesting changing in maximum numbers (for vCenter in linked-mode) and an interesting news for the Foundation edition that now can manage up to 4 nodes (and not only 3 nodes like in the past).

Seems a minor improvement, but demostrare how VMware takes care of its customers. In discussions with customers with smaller environments, VMware has received feedback that 3 host environments were too small in many cases, and just another hosts could be enough (of course still for SMB enviroments).  This is why with vSphere 6.5 Update 1 VMware is now increasing the number of hosts that vCenter Server Foundation will support from 3 host to 4.

What are the possible implication of this? With 4 nodes you can do interesting thinks that you can now plan in your design:

  • vSAN cluster: technically 3 nodes are the minimum, but I don’t like too much build a vSAN cluster with only 3 nodes… I prefer have 4 in order to plan a better resiliency
  • vSAN 2 nodes cluster: make sense have just a cluster with 2 nodes, the witness appliance on a 3rd node and manage both the 3rd node and the witness with the same vCenter? Maybe yes or, let’s say… why not… now it can be considered
  • Production and DR cluster: also with 3 nodes was possible, but limited to 2+1, in this case you have more flexibility
  • Scale out instead of scale in: will make sense have more hosts (maybe with single processor) instead of few?

And a vSAN stretched cluster could be possible? Seems crazy, and out of the scope of SMB, also because you need ESXi with Enterprise Plus, but those can be managed by a Foundation license. The issue is the witness, you need a 3rd site with the witness, and it but could stay on a free hypervisor or on a cloud resourse, but how you can manage it if you already have 4 connected nodes, and to set up the stretched cluster you need also the witness inside the SAME vCenter.

Note that the Essential edition of vCenter remain still limited to only 3 nodes, and that ESXi Essential or Essential Plus can only be managed by vCenter Essential (this limitation has become also a technical limitation starting with vSphere 5.x).