We will be rolling out vSphere ESXi 4.0 to dozens and dozens of small remote offices. 90% will consist of a single ESXi host running 2-3 VMs. We are trying to decide in vCenter Hosts and Clusters how many 'datacenters' to make. We have two 'true' datacenters in the physical sense of the word and they have their own vCenter Datacenters. We were thinking of creating a single 'remote office' DC under which we would put all remote office ESXi hosts. Administration is centralized, so delegation isn't a huge problem. We will end up with 100+ remote ESXi hosts.
Is there a big advantage or disadvantage to creating 100+ DCs or just lump them together under one? We want to minimze the work during a new site installation, as well. We are leaning towards a single 'remote office' DC as it seems simpler.
If you need to keep it simple use a single datacenter.
Datacenter are useful for delegation, for geographic/logical separation, and so on...
But you can choose to use them or not...
DC are great for delegation of rights, but they will limit you in the long run.
You can not Vmotion etc between datacentres, so creating the additional DCs will only remove features.
I'd suggest just creating folders for the remote offices and then assigning rights accordingly (if you need to)
Actually, I'm now leaning towards datacenters for each remote location. As you pointed out, you can't vMotion between datacenters. Since its impossible to vMotion between our physical locations, making them datacenters could prevent 'oops' mistakes of trying to vMotion across the WAN which would fail. Of course within a physical location that has a lot of ESX hosts, they will be contained within one datacenter and broken down into folders for organization.