Physical location
No, Public Clouds are not located in the clouds (I think that was obvious but it doesn’t hurt to point it out). Public Clouds are hosted in dedicated Data Processing Centres (DPCs) in strategic locations, based on multiple factors such as geographical location and environment, like any DPC intended for Private Clouds or other services.
For security reasons, a DPC could not be located very close to an airport or a reservoir. They also tend to choose locations where there is a connectivity node nearby to minimise network latencies and where there are several fibre operators so that there is redundancy in communications. The site must have electricity, water, as well as adequate weather conditions to support cooling (a desert would not be an option because of the heat, among other things). Additionally, it must also be an area with low seismic activity, free of tornadoes and, if possible, with good road access (close to a motorway, for example). All these studies are carried out in the design phase.
Yes, there is ‘El Hierro’
Just as we have said that Public Clouds are hosted in DPCs, the computing and storage infrastructure behind them is completely physical. That is to say, like any traditional DPC, we have racks, servers, storage cabinets, routers, switches, etc. The Public Cloud adds the layer of virtualisation, redundancy, pay-per-use billing and the ‘as a service’ for some elements.
Resource limits
Although it may seem that we can grow in the cloud without a ceiling to stop us, I have to tell you that this is not the case. Yes, resources in the Public Cloud are also limited. However, there is a very aggressive capacity plan behind the scenes that is anticipated well in advance, to carry out the provisioning and installation of the physical resources necessary so that they are available to us in a totally transparent way, before the current ones are occupied. Despite this, there are times when the DPC does not have the physical space to accommodate new elements and the DPC building itself has to be expanded to accommodate everything new, so growth could be temporarily limited in some regions. This already happened during the COVID-19 pandemic, when the DPCs in some regions became oversaturated as many companies made a very rapid transition to the Public Cloud and the occupation was faster than the provisioning of new resources.
Not all resources are public or shared
Even if it is Public Cloud, this does not mean that the elements are always exposed to the internet. The resources can be configured in such a way that they can only be accessed from private addressing or VPN, or even that the exit to the internet is routed by on-premise, treating the Public Cloud as if it were just another site in the company’s MPLS, totally isolated.
In the same way, certain resources such as virtual machines can be deployed in dedicated infrastructure (dedicated and isolated hardware) as if it were a Private Cloud. Of course, this carries a significant additional cost.
