Potentially, you can centralize everything in the main office (or in a public cloud) environment. Maybe the desktop could also be centralized, using VDI or some kind of RemoteApp. From a management point of view, this solution is easy, just because all is centralized and managing and monitoring will be easier. Also, backup, data protection, and availability could be better managed.

But there can be some risks—network connectivity becomes much more critical, not only from the bandwidth point of view (where you need enough bandwidth for each service and each user), but also, because latency and reliability can impact the business continuity requirements and user experiences in the worst way. If the risk is too high, local workloads are needed at the remote offices.

In ROBO scenarios, a reasonable availability level could be between 99% and 99.9%, but there are some workloads that may require the higher level (or others that are not critical at all). The vSphere HA features could be enough for most cases.

Performance isn’t usually a problem, due to the computing capacity of a common server today; a single host can potentially handle all the workloads, but of course, it also represents a single point of failure. For this reason, the two host configuration is the most typical for this scenario. The sizing of those hosts is not usually critical, and reducing the cost could also be interesting, considering single socket configurations. Fresh air cooling technology could be useful, and in some cases, also enough.

Storage is more tricky, due the budget constraints and also the possible space constraints; you still need storage with reasonable reliability and shared capabilities, in order to use a VMware cluster, but a good external storage could be costly and provide more complexity in the infrastructure (external switches, more components, and so on). Fortunately, there are some specific hyper-converged solutions for ROBO scenarios, both from VMware (vSAN for ROBO configuration, with a specific license based per VM) and other vendors (for example, StorMagic and StarWind).

In ROBO scenarios, it is usually really important to minimize the license cost of each office, in order to keep the entire project in the estimated budget. Cost per VM or space could be interesting, considering the low number of them.

The VMware vSphere ESXi licenses that are most interesting for remote offices are the ROBO SKU that are sold per VM (25 VMs SKU). ROBO advanced is around €180 per VM; that is cheaper (for few VMs) compared to ESXi Standard (around  € 1000 for one socket), or the Essential Plus Kit (less than € 4500 for three hosts and six sockets). The ROBO license is independent of the number of hosts or sockets or cores, but please note that each VM counts as a license, including management VMs (like VSA or other VA).

Windows Server licenses remain per socket (and, starting with Windows Server 2016, also limit the total number of cores). With just a couple of VMs, Windows Standard edition could be considered, to limit costs.

Storage licenses depend on the type of storage; it can be included in the cost of the storage itself, but for software-based storage like vSAN or other VSA based storage, it can be licensed in different ways—per capacity (like several VSA solutions), per socket (like vSAN), or also per VM (like vSAN for ROBO).

For VMware vSAN, again, the ROBO SKU could be interesting for a small number of VMs in each remote office (around €500 per VM), compared to the other license option (starting from €2,500 per socket for the Standard edition).