HI,
Prepare an outline of what these vCenters are like (Esxi, Virtual machine), region by region.
- Check the occupied and free space in the datastores.
- Check the total Ram for each Esxi and how much is occupied.
- Also check the occupied and free CPUs.
- Check the Network configurations that are on ESXi \ vCenter, VDS, VSS, VLANs
If you have to unify all the regions in a single point, you must also think about a possible increase in network bandwidth, because I would have more data traffic.
All this information, together with the badget you have available, allows you to configure suitable hardware.
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Another info that I want to give you is to also evaluate a vCenter solution in HA (to limit damage in case of failure)
VMware vCenter 6.7 High Availability Configuration – PART 1
ARomeo